Answers to Challenging Infrastructure Management Questions

Answers to Challenging Infrastructure Management Questions Report #4367 Subject Area: Infrastructure

Answers to Challenging Infrastructure Management Questions

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Answers to Challenging Infrastructure Management Questions Prepared by: Dan Ellison, Graham Bell, Steven Reiber, and David Spencer HDR, 701 E. Santa Clara Street, Suite 36, Ventura, CA 93001 Andrew Romer AECOM, 999 Town and Country Rd., Orange, CA 92868 John C. Matthews Battelle Memorial Institute, 7231 Palmetto Dr., Baton Rouge, LA 70808 Ray Sterling Louisiana Tech University (retired), P.O. Box 10348, Ruston, LA 71272 and Samuel T. Ariaratnam Arizona State University, P.O. Box 875306, Tempe, AZ 85287-5306 Jointly sponsored by: Water Research Foundation 6666 West Quincy Avenue, Denver, CO 80235 and U.S. Environmental Protection Agency Washington, D.C. Published by:

DISCLAIMER This study was jointly funded by the Water Research Foundation (WRF) and the U.S. Environmental Protection Agency (EPA) under Cooperative Agreement No. EM 83406801-1. WRF and EPA assume no responsibility for the content of the research study reported in this publication or for the opinions or statements of fact expressed in the report. The mention of trade names for commercial products does not represent or imply the approval or endorsement of WRF or EPA. This report is presented solely for informational purposes. Copyright 2014 by Water Research Foundation ALL RIGHTS RESERVED. No part of this publication may be copied, reproduced or otherwise utilized without permission. ISBN 978-1-60573-204-6 Printed in the U.S.A.

CONTENTS LIST OF TABLES... xiii LIST OF FIGURES... xv FOREWORD... xix ACKNOWLEDGMENTS... xxi EXECUTIVE SUMMARY... xxiii CHAPTER 1 - INTRODUCTION... 1 Project Approach... 2 How big is the problem How well are we keeping up with our infrastructure?... 3 How does infrastructure affect the distribution system?... 3 What are the benefits of an infrastructure assessment and renewal program?... 4 Economy... 4 Water Quality... 4 Customer Satisfaction... 5 Improved Fire Low and Hydraulics... 5 Why did the pipe break on Maple Street? What are you doing about it?... 5 What does the future hold?... 6 CHAPTER 2 - ASSET MANAGEMENT... 7 What Exactly is Asset Management? Where can I learn about it?... 7 How do I plan for future infrastructure replacement?... 8 Given limited resources, what data should I focus on first?... 9 What is a leak? What is a break? Are terminology and data conventions holding the industry back?... 10 What data should I be collecting related to repairs?... 10 What other data may be useful for decision making?... 11 With these data, can I predict when a pipe will break?... 11 Can t we use artificial intelligence to figure this out?... 14 How do I store and manage these data?... 14 How should asset data be organized?... 15 How long will my pipes last?... 15 How do I estimate useful life expectancies?... 16 Other sources of information on asset life prediction... 23 What does experience tell us about the useful lives of pipe? Are expectations increasing? 23 When should a pipe be replaced?... 24 Rules of Thumb / Trigger Points... 25 Shouldn t we consider other costs? What about the triple bottom line?... 26 Costs of infrastructure failure... 26 What about the value of maintaining a reputation for excellent service?... 26 v

vi Answers to Challenging Infrastructure Management Questions Are customers really willing to pay for this service?... 27 How do these service levels compare to industry performance?... 27 What is an appropriate level of service for main repair rates?... 27 What tools can assist in determining an appropriate service level?... 28 How do the concepts of risk management apply to infrastructure renewal decisions?... 29 Risk Evaluation Concepts... 30 What does "risk management" really mean?... 34 How do I budget for infrastructure replacement?... 35 If the future program appears unaffordable, what can be done?... 37 How will I know if the renewal level is adequate?... 38 What happens if we do nothing?... 39 AWWU Case Study: How Asset Management and Condition Assessment Reduced the Financial Burden Facing One Utility... 39 How do I select pipes for assessment or renewal?... 41 Other Factors to Consider in Selecting Pipes to Assess and Renew... 42 How important are leak data and leak management?... 42 How do I know that I'm managing my system effectively?... 43 Other sources of information for system performance evaluation... 43 Besides the break rate and water loss percentage, what other metrics can be used?... 44 How can I compare our operations to others?... 44 Portland Water Bureau Case Study: Developing the tools and processes to measure performance... 45 CHAPTER 3 - MATERIAL PERFORMANCE AND CORROSION PROTECTION... 49 What causes pipes to fail?... 49 What are the loads that fail pipe?... 49 Internal Pressure... 49 Beam Bending... 50 Temperature... 50 External Loading... 51 Fatigue... 51 What are the aging processes associated with water pipes?... 51 Iron pipe aging... 53 Steel Aging and Corrosion Protection... 58 Stray Current Corrosion... 58 PVC Aging... 59 Polyethylene aging... 60 Asbestos Cement Pipe Aging... 62 Concrete Pipe Aging... 65 What factors drive or slow metal corrosion?... 68 What are the life expectancies of different pipe materials?... 70 Comparison of Main Repair Rates... 71 How do the failure rates of different pipe material compare in North America?... 72 How do future failure rates compare?... 73 Future PVC Failures... 73 Future HDPE Failures... 74 Future Ductile Iron Failures... 75

Contents vii Why is Portland cement so effective in corrosion protection of pipes?... 76 How long will the cement mortar lining last?... 76 How well do the different pipe materials perform in earthquakes?... 77 Can I make the new pipes last longer?... 78 Can I make the existing pipes last longer?... 79 Lining Programs... 79 CP System Retrofits... 79 Pressure Management... 80 Water Conditioning... 80 Break Repair Anodes... 80 How do the failure consequences of different materials compare?... 80 Crack Propagation... 81 In summary, which pipe material performs best for water mains?... 82 What pipe should I use for service lines?... 83 How long do valves, hydrants, and other system appurtenances last?... 84 How long will tanks and reservoirs last?... 85 Corrosion Protection of Steel Tanks and Steel Roof Structures... 85 Aging Processes for Concrete Tanks and Reservoirs... 86 Mitigating concrete deterioration... 88 What causes tanks and reservoirs to fail?... 89 How well do tanks and reservoirs perform in earthquakes?... 89 CHAPTER 4 - WATER QUALITY AND INTERNAL CORROSION... 91 How do I assure that good quality water arrives at the tap?... 91 Are health issues associated with dirty water events?... 93 What makes water aggressive?... 94 With all those factors, how can I tell whether my water is aggressive?... 96 Can the corrosivity of the water be measured?... 96 Should the water be conditioned so it s less aggressive?... 97 What corrosion inhibitors work best for copper and lead?... 98 What corrosion inhibitors work best for cement mortar linings, AC pipe, and other concrete pipe?... 99 Does the use of corrosion inhibitors have any deleterious side effects?... 99 What's the best way to reduce lead?... 99 Does partial lead service line replacement (PLSR) make sense?... 100 Should water mains be cleaned?... 101 How should pipes be cleaned?... 101 Unidirectional Flushing... 101 Air Scouring... 102 Ice Pigging... 103 Swabbing and Pigging... 103 Cleaning and Lining... 104 Other Cleaning Methods... 104 How often should a system be flushed?... 104 How can I diagnose a water quality complaint?... 105 What causes depletion of disinfectant in the system?... 105 What causes pitting on copper service lines and domestic plumbing?... 107

viii Answers to Challenging Infrastructure Management Questions What creates blue water? How can it be eliminated?... 108 Has simultaneous compliance with various regulations (DBP and TCR) adversely influenced corrosion control?... 108 What are the utility s obligations in responding to customer water quality and corrosion complaints?... 195 How does a utility protect itself from litigation?... 109 How well do plumbing materials perform?... 110 What s a reasonable service life for distribution and domestic plumbing?... 110 Can dezincification of brasses be controlled through corrosion control efforts?... 111 What are the challenges of integrating (blending) new water supplies into old systems?... 111 How does re-equilibration relate to corrosion?... 112 What parts of the distribution system are at greatest risk of re-equilibration issues?... 113 What about desalinated water and re-equilibration?... 113 How do issues of water age affect water quality?... 113 Perception versus reality: Is the nation s drinking water quality degrading?... 114 CHAPTER 5 - CONDITION ASSESSMENT... 115 How should the overall health of the system be assessed?... 116 Desk-Top Reliability Studies... 116 Where should a detailed condition assessment be performed?... 117 Root-Cause Analysis of Failures... 118 Statistical Analysis of Failures... 119 Supplemental Data Collection... 119 Prioritization Model... 119 How do I justify the cost of condition assessment?... 120 How do I do a detailed condition assessment project?... 121 Step 1. Project Planning... 121 Step 2. Initial Assessment... 121 Step 3. Field Inspections... 122 Step 4. Engineering Analyses... 122 Step 5. Renewal Planning... 123 How should small mains be assessed?... 123 Leveraging NDE Data for Assessing Small Diameter Pipelines (WaterRF Project 4471)... 123 The Assess-and-Fix Approach (WaterRF Project 4473)... 124 What field assessments are recommended?... 124 How should the Structural Integrity of iron and steel mains be assessed?... 126 Soil Corrosivity Testing... 126 Pipe-to-soil Potential Measurements... 126 External Direct Assessment... 127 External Structural Condition Inspection Tools for Iron and Steel Mains... 128 Integrity Testing using Controlled Destructive Examination of Iron and Steel Mains... 129 In-pipe NDE Methods for Iron and Steel Mains... 130 How should the condition of asbestos cement pipe be assessed?... 132 How can the condition of Polyvinyl chloride (PVC) pipe be assessed?... 132

Contents ix How can the condition of HDPE be assessed?... 133 Isn t there an inexpensive, non-invasive method for small mains?... 133 Acoustic Velocity Testing... 133 How can I determine the condition of a prestressed concrete pipe?... 135 Remote-field transformer-coupled (RFTC)... 135 Acoustic emission monitoring... 136 Manned in-pipe inspection and sounding... 136 Seismic Pulse Echo... 136 What techniques can be used on non-prestressed concrete pipe?... 136 How do I assess a large-diameter pipe that cannot be taken out of service?... 137 Why aren't these NDE devices more commonly used?... 137 City of Calgary Case Study Using NDE to Guide a Small Main Renewal Program... 138 What does a detailed condition assessment of a pipeline cost?... 140 Should I look for leaks?... 140 How do I find leaks?... 141 Water Loss Audits and Leakage Analysis... 141 Leak Surveys... 141 Leak detection equipment? Digital correlators?... 141 In-pipe leak detectors... 142 What about continuous leak detection?... 142 Acoustic Sensor Data Loggers... 142 Automatic Meter Reader (AMR) Systems... 143 Combination acoustic and AMR systems... 143 Other Leak Detection Tools... 143 How do I locate the pipes?... 144 Metal Detectors... 145 Ferromagnetic Locators... 145 Radio Transmission Locators... 145 Ground Penetrating Radar... 146 Other Nonmetallic Pipe Locators... 146 Pot holing and vacuum excavation... 146 How do I assess soil corrosivity?... 147 Electromagnetic conductivity survey... 147 Electrical resistivity tests along the alignment by the Wenner Four-Pin Method... 148 Laboratory tests on soil samples... 148 Linear Polarization Resistance (LPR)... 148 Stray-current Evaluation... 149 Can I tell how fast a pipe is corroding?... 149 Can I tell if the corrosion protection systems are working?... 150 Evaluation of Existing Cathodic Protection Systems... 150 In-situ Evaluation of Coating Performance... 150 Should I dig down to the pipe to assess its condition?... 150 Should I do coupon testing?... 151 Pipe Coupon Removal... 151 Coupon Insertion... 152

x Answers to Challenging Infrastructure Management Questions Should I put a camera inside the pipe?... 152 Can I monitor the performance of pipelines and detect impending failures?... 153 How can I assess the condition of pipeline joints?... 153 Before testing a pipe, what other issues should be considered?... 154 How, and how often, should I inspect my valves and hydrants?... 155 How do I evaluate tanks and reservoirs?... 155 Steel Tanks and Structures... 155 Concrete tanks and reservoirs... 157 Health-issues and other concerns... 157 How should pump stations and treatment plants be evaluated?... 158 CHAPTER 6 - PIPELINE RENEWAL METHODS... 161 If pipe rehabilitation is so great, why isn t it used more?... 161 What does a typical rehabilitation project involve?... 162 What methods should I use for pipeline renewal?... 162 In-Situ Cement Mortar Lining... 164 Epoxy and Other Polymer Linings... 165 Structural Liners / Trenchless Replacement... 166 How do I choose among the various lining methods?... 172 What other rehabilitation alternatives exist?... 173 Cathodic Protection Retrofits... 173 Spot Repairs and Segment Replacements... 174 Can rehabilitation strengthen the pipe?... 174 How do I design a pipe lining?... 175 Non-structural lining design... 176 Design of fully-structural rehabilitation... 176 Semi-structural lining design... 176 How do the various lining materials perform?... 177 Cement mortar linings... 177 Non-Structural Polymer linings... 177 Structural lining materials... 177 Semi-Structural Systems... 178 What factors are hindering greater use of rehab for water mains?... 178 After rehabbing a pipe, how do I reconnect services without digging holes up and down the street?... 179 Can I line through valves and fittings?... 180 How do I keep customers supplied during a rehab project?... 180 What other trenchless methods can be used for water pipes?... 182 Horizontal directional drilling (HDD)... 182 Jack-and-bore... 182 Pipe ramming... 182 Tunneling/microtunneling... 182 Pilot-tube microtunneling... 182 Piercing tools/moles... 182 Service line pulling or splitting... 182 Should I clean my pipes? How should I clean my pipes?... 182 Should tuberculation be removed?... 183

Contents xi How do I get a pipeline renewal project started?... 184 Construction Management and Inspection... 185 CHAPTER 7 - MANAGING A WATER MAIN RENEWAL PROGRAM... 187 How do I build a case for a proactive renewal program?... 187 How much money will I need?... 187 How do I sell the program to my customers and the board?... 188 How can I fund my program?... 189 Bonding... 189 Rate surcharges... 189 Redevelopment Programs... 190 Developer Funding... 190 Public / Private Partnerships... 190 Government grants and loans... 190 Long-term maintenance and warranty programs... 190 Once I get the money, what s the best way to spend it?... 191 What else is important in delivering a first-rate program?... 192 Customer-first attitude... 192 Hold the contractor responsible... 192 Say no to petty contractor claims... 192 Make provisions for the genuine extra work that will occur... 194 Trust, but verify... 195 Ask your customers for a report card... 195 Celebrate successes... 196 APPENDIX A - COMMON WATER SYSTEM CORROSION PROCESSES... 197 Galvanic (or bimetallic) corrosion... 197 Galvanic series... 197 Cathode and anode size... 197 Corrosion pitting and rust holes... 198 Cathodic protection... 198 Passivation... 198 Stray-current corrosion... 199 Leaching... 199 Sulfate Attack of Concrete... 200 Alkali-Silica Reaction... 200 Tuberculation... 200 APPENDIX B - TYPICAL GALVANIC SERIES... 201 APPENDIX C - RISK MANAGEMENT TOOLS USED BY WSSC AND SPU... 203 Washington Suburban Sanitary Commission (WSSC)... 203 Seattle Public Utilities (SPU)... 204 REFERENCES... 213 ABBREVIATIONS... 223

LIST OF TABLES 2.1 Various pipe life expectancy benchmarks... 21 2.2 Factors Used in Assessing Pipe Failure Risk... 34 2.3 Results of KANEW Analysis for 5 Water Systems... 37 2.4 Benchmarking Metrics Used in 2011 AWWA Survey of Members... 45 3.1 Summary of Water Pipe Aging and Failure Processes... 52 3.2 Factors Which Promote or Retard Corrosion... 69 3.3 Factors Which Affect Soil Corrosivity... 70 3.4 Water Main Failure Rates in the UK... 72 3.5 General Comparison of Seismic Performance of Common Water Main Materials... 78 3.6 General Comparison of Risk Factors for Common Water Main Materials... 82 3.7 Tank/Reservoir Seismic Vulnerabilities... 90 4.1 Factors Which Affect Water Corrosivity... 94 4.2 Comparison of Common Water Main Cleaning Methods... 101 5.1 Water Main Aging Processes and Field Assessment Methods... 125 5.2 Assessments of Pump Stations and Plants... 158 6.1 Common Water Main Rehabilitation Methods... 163 xiii

LIST OF FIGURES 2.1 SAM-GAP analysis example... 8 2.2 Infrastructure renewal planning... 9 2.3 Contrasts in pipe deterioration... 16 2.4 Example of performance modeling for two asset classes... 17 2.5 Example of Weibull failure modeling of a medium-sized water system... 19 2.6 Illustration of the Yule effect... 20 2.7 The downward trends in LADWP main leak and break rate... 24 2.8 The return on investment model for asset replacement... 25 2.9 The LADWP shot seen round the world... 29 2.10 The two dimensions of risk... 31 2.11 A relative risk assessment system... 31 2.12 The consequences of failure of a 66-inch transmission main near Washington, DC in 2008... 32 2.13 Relative Risk vs. Pipeline Size... 33 2.14 Example of Nessie curve... 36 2.15 Pipe installation history, Ventura, California... 38 2.16 Example of a long-term break for a medium-sized city... 39 2.17 Information value chain... 40 2.18 Comparison of planning-level asset renewal estimates, before and after statistical analysis of pipe longevity in the AWWU system... 41 2.19 Comparison of Portland Water Bureau with other project participants in International Asset Management Performance Improvement Project... 46 xv

xvi Answers to Challenging Infrastructure Management Questions 2.20 Comparison of Portland Water Bureau s 2008 and 2012 results in International Asset Management Performance Improvement Project... 47 3.1 Minimum wall thicknesses for 36-inch iron pipe... 54 3.2 One-inch diameter through hole revealed by grit blasting 6-inch ductile iron pipe... 54 3.3 Predicted pit growth for ductile iron pipe in moderately corrosive soil... 55 3.4 The effects of pit growth for ductile iron pipe in moderately corrosive soil... 56 3.5 PVC failure mechanism... 59 3.6 Phenolphthalein stain tests and SEM/EDS results for degraded AC pipe... 63 3.7 Relationship between AC pipe degradation and strength... 64 3.8 Year of manufacturer versus failure rates for PCCP... 67 3.9 The evolution of standards for PCCP... 68 3.10 Comparison of North American failure rates... 73 3.11 Predicted PVC failure rates... 74 3.12 Predicted HDPE failure rates... 75 3.13 Examples of increasing and steady rates of ductile iron failure... 75 3.14 A tale of two tanks illustrates the importance of quality coating work... 86 3.15 Alkali-silica reaction cracking of a concrete tank... 87 4.1 Heavily scaled 80-year old cast-iron main... 92 4.2 Accumulation and release of distribution system contaminants... 93 4.3 Comparison of conventional and unidirectional flushing techniques... 102 4.4 Air scouring... 103 4.5 Pipe cleaning pigs... 104 4.6 Diagnostic chart for distribution water quality problems... 106 5.1 Unlined cast-iron main, installed in 1926 and rehabilitated in 2005... 115

List of Figures xvii 5.2 Water distribution network assessment... 116 5.3 Spatial distribution of AC pipe failures in the East Bay Municipal Utility District... 117 5.4 Pipeline condition assessment model... 118 5.5 Tradeoffs between degree of inspection and inspection coverage... 121 5.6 Condition assessment of water mains can be considered a 5-Step process... 121 5.7 Remote-field electromagnetic tool used for 6-inch ductile iron pipe assessment... 124 5.8 Cathodic Protection Test Station... 127 5.9 External direct assessment of mortar coated steel water pipeline... 127 5.10 Remote-field electromagnetic scanning... 130 5.11 Schematic illustrating magnetic flux leakage... 131 5.12 In-pipe broadband EMT device and output... 132 5.13 Acoustic thickness and leak testing using noise correlators at LADWP... 134 5.14 Map showing water mains scanned in the City of Calgary... 139 5.15 Ground penetrating radar image... 146 5.16 Corrosion engineer performing an electromagnetic survey... 148 5.17 Live insertion of combination video/acoustic sensor at fire hydrant... 152 5.18 Example of tank float inspection... 156 6.1 Cement mortar lining (before and after)... 165 6.2 Epoxy lining (before and after).... 166 6.3 HDPE sliplining.... 167 6.4 Deforming a 24-inch HDPE pipe for tight-fit HDPE lining... 168 6.5 Pipe bursting... 170 6.6 Internal Joint Seal... 172

xviii Answers to Challenging Infrastructure Management Questions 6.7 Pipe bending test of CIPP lining under pressure... 175 6.8 Using the pit-growth model to forecast future deterioration... 178 6.9 Keyhole methods... 179 6.10 Bypass Piping... 180 6.11 Pipe cleaning pig emerging from a fire hydrant... 183 7.1 Post project customer survey card... 196 A.1 Elements of a Battery... 197

FOREWORD The Water Research Foundation (WRF) is a nonprofit corporation dedicated to the development and implementation of scientifically sound research designed to help drinking water utilities respond to regulatory requirements and address high-priority concerns. WRF s research agenda is developed through a process of consultation with WRF subscribers and other drinking water professionals. WRF s Board of Trustees and other professional volunteers help prioritize and select research projects for funding based upon current and future industry needs, applicability, and past work. WRF sponsors research projects through the Focus Area, Emerging Opportunities, and Tailored Collaboration programs, as well as various joint research efforts with organizations such as the U.S. Environmental Protection Agency and the U.S. Bureau of Reclamation. This publication is a result of a research project fully funded or funded in part by WRF subscribers. WRF s subscription program provides a cost-effective and collaborative method for funding research in the public interest. The research investment that underpins this report will intrinsically increase in value as the findings are applied in communities throughout the world. WRF research projects are managed closely from their inception to the final report by the staff and a large cadre of volunteers who willingly contribute their time and expertise. WRF provides planning, management, and technical oversight and awards contracts to other institutions such as water utilities, universities, and engineering firms to conduct the research. A broad spectrum of water supply issues is addressed by WRF's research agenda, including resources, treatment and operations, distribution and storage, water quality and analysis, toxicology, economics, and management. The ultimate purpose of the coordinated effort is to assist water suppliers to provide a reliable supply of safe and affordable drinking water to consumers. The true benefits of WRF s research are realized when the results are implemented at the utility level. WRF's staff and Board of Trustees are pleased to offer this publication as a contribution toward that end. Denise L. Kruger Chair, Board of Trustees Water Research Foundation Robert C. Renner, P.E. Executive Director Water Research Foundation xix

ACKNOWLEDGMENTS The authors of this report wish to acknowledge the contributions of the many researchers and authors whose works are the subject of this report. Special thanks are due the following people and organizations who gave time, materials, and effort directly to this project: Water Research Foundation Project Manager: Frank Blaha, Water Research Foundation, Denver, CO Water Research Foundation Project Advisory Committee: Christina Miller, Anchorage Water and Wastewater Utility, Anchorage, AK Jared Heller, Advanced Engineering and Environmental Services, Inc., Moorhead, MN Jeff Leighton, City of Portland, Water Bureau, Portland, OR Participants in Workshop 1, Cal/Nevada AWWA Conference, Reno, NV, Oct.17, 2011 Craig Close, HDR Engineering, San Diego, CA Heather Collins, California Department of Public Health, Los Angeles, CA Uzi Daniel, West Basin Municipal Water District, Carson, CA Nass Diallo, Las Vegas Valley Water District, Las Vegas, NV Andy Ferrigno, City of Huntington Beach, Huntington Beach, CA Stephen D. Gay, Long Beach Water Department, Long Beach, CA Duncan Lee, City of Huntington Beach, Huntington Beach, CA Jonathan Leung, Los Angeles Department of Water & Power, Los Angeles, CA David Lippman, Las Virgenes Municipal Water District, Calabasas, CA Jason Lueke, Arizona State University, Tempe, AZ John R. Plattsmier, HDR Engineering, Denver, CO Dave Rexing, Las Vegas Valley Water District, Las Vegas, NV J.R. Rhoads, Metropolitan Water District of Southern California, Los Angeles, CA Jim Simunovich, Cal Water Service Company, San Jose, CA Shonna Sommer, Calleguas Municipal Water District, Thousand Oaks, CA Jim Wollbrinck, San Jose Water Co., San Jose, CA Ron Zegers, Las Vegas Valley Water District, Las Vegas, NV Participants in Workshop 2, AWWA Annual Conference, Dallas, TX, June 10, 2012 Marty Allen, Water Research Foundation, Denver, CO Terry Benton, City of Arlington, Arlington, TX Greg Kirmeyer, HDR Engineering, Bellevue, WA David Lippman, Las Virgenes Municipal Water District, Calabasas, CA Jason Lueke, Arizona State University, Tempe, AZ Ken Morgan, City of Phoenix, Phoenix, CA John Plattsmier, HDR Engineering, Denver, CO Kurt Vause, Anchorage Water and Wastewater Utility, Anchorage, AK [Workshop participants also included the Research Team, Project Advisory Committee, and WaterRF Project Manager.] xxi

xxii Answers to Challenging Infrastructure Management Questions Other Contributors: Roy Brander, City of Calgary, Calgary, Alberta, Canada John Galleher, Pure Technologies, Inc., San Diego, CA Joseph Loiacono, Sanexen Environmental Services, Inc., Longueuil, Quebec, Canada Lynn Osborn, Aegion Corporation, St. Louis, MO David Rosenberg, Aegion Corporation, St. Louis, MO Camille Rubeiz, Plastics Pipe Institute, Irving, TX Daniel Smith, WaterOne, Lenexa, KS Tracy De La Torre-Evans, Seattle Public Utilities Fred Pfeifer, Washington Suburban Sanitary Commission

EXECUTIVE SUMMARY How can a water utility achieve the support needed for an effective infrastructure program? This is the most challenging infrastructure question overall, voiced repeatedly in project workshops. Lack of adequate funding limits what gets assessed and what gets renewed. With the pipes and other assets growing older, maintenance and replacement needs are sure to go up, yet utility customers feel they already pay enough for the water and service they receive. Can they be persuaded to pay more or should industry service levels decrease? There is, of course, no single, easy answer to this question, but neither is it unsolvable. Indeed, most utilities have achieved acceptable short-term answers to this question. These utilities are delivering water to customers, keeping facilities running, and completing necessary repairs, while staying within their budgets. For most utilities, asset failures are not yet out of control. But are these short-term solutions the best answers? Is the right level of renewal occurring, or are problems simply being deferred? Should we be spending more in the shortterm, so that long-term burdens are lessened? What is the best way to balance customer needs and utility resources when looking toward the future? Utilizing the research of dozens of WaterRF projects and other sources, this report provides an overview of the issues and approaches utilities can take to answer these questions. To achieve support for an effective infrastructure program, the utility must make a compelling case, founded on intelligent analyses and reliable data, and the case needs to be communicated in a way that both the technical and non-technical stakeholders can understand. There are many right ways to do this. Perhaps the only wrong approach is to do nothing. OBJECTIVES This report is intended as a synthesis document, meaning it summarizes and integrates the research from numerous WaterRF reports and similar technical documents. An implied objective is to make the research both understandable and practical, something that utility managers and engineers who are not experts in infrastructure management will find both informative and interesting, with applications to their day-to-day responsibilities. Following the format of several similar projects, this report is presented in a question-and-answer format, with the hope that this provides quick-to-find answers to a variety of questions. Additionally, the text is organized so the answer to one question leads to the next question, making the report readable to the extent that any technical report about pipes, valves, and tanks can be. The selected topics are those of common interest to infrastructure managers, and include asset management, corrosion, materials performance, water quality impacts, condition assessment, rehabilitation, and program management. The focus is primarily on water mains, but other types of assets are also discussed. In some cases, where scientifically supported conclusions do not exist, the answers border on opinion, but these opinions are guided by the research. BACKGROUND In some ways, this is the second edition of Distribution Infrastructure Management: Answers to Common Questions, a WaterRF report published in 2001. This earlier report was xxiii

xxiv Answers to Challenging Infrastructure Management Questions written when the field of asset management was in its infancy and most utilities in the US were just starting to realize that aging infrastructure was a concern. Prior to this earlier study, the Water Research Foundation had published about a dozen reports directed at infrastructure issues, but subjects were sometimes narrow, and valuable information within these reports was often overlooked. Much has changed in the dozen years since the publication of this earlier report. Awareness of infrastructure needs has increased, and asset management is now the norm, not the exception, but utilities still struggle with the same fundamental questions: How long will our pipelines last? Which pipes should be renewed? What are the best ways to renew our pipes? How much money is needed? This new report, Answers to Challenging Infrastructure Questions is an update of this earlier project, but with somewhat different emphases. Infrastructure research has exploded during the intervening decade; so while some of the original content has been retained, there is considerable new knowledge to help answer these fundamental questions. PROJECT APPROACH Three sources were used to develop the lists of issues and questions discussed in the current report: 1. The questions from the 2001 report were reviewed by both the Research Team and the Project Advisory Committee. Important questions were kept, but some were modified for editorial reasons. Admittedly, not all these questions are technically challenging, but they provide context for the overall discussion. 2. An independent list of questions was developed at a project workshop attended by infrastructure experts and managers from several leading utilities from across the US. 3. A comprehensive review of Water Research Foundation reports was completed, and from this a list of general questions was derived. From these three sources, a master list was compiled and further discussed at another workshop, where infrastructure experts looked for gaps and discussed relevant research. The answers to the questions come primarily from the WaterRF projects referenced herein. These answers have been formulated and reviewed by a team of well-regarded water infrastructure experts. RESULTS/CONCLUSIONS This report provides an overview of infrastructure management concepts and research, including how data can be gathered, stored, and analyzed; how common materials deteriorate; how the condition of assets can be assessed; how system components can be renewed economically; and how a program can be managed. Among the major questions answered by this report are:

Executive Summary xxv How long does a water main last? Answer: A water main lasts until someone decides to replace it, and the decision to replace it should be based on economic, environmental, and social considerations. Social considerations include the levels of service acceptable to the utility s customers, the levels of risk appropriate for the utility, and long-range financial sustainability. What data are needed for intelligent water main replacement decisions? Answer: While an abundance of data is desired, good decisions can be made with limited data. Main repair data and other available data can be used to predict remaining service lives, set replacement budgets, evaluate risks, and select mains for further investigation or for renewal. Then, as more data are gathered, these analyses can be revisited, management plans revised, and long-range decisions fine-tuned. What pipe materials perform the best? Answer: When used appropriately, all common water main materials (ductile iron, steel, PVC and HDPE) can provide very good long-term performance. With conservative engineering, good workmanship, and effective quality assurance, life expectancies well beyond 100 years are achievable. Unfortunately, the water industry has not mandated that long-term performance be the basis for design. Historic changes in AWWA standards have often produced pipes with reduced service lives. What should be considered in selecting a pipe material? Answer: The purchase cost of the pipe material should be a very minor consideration. When constructing a replacement main in a developed area, most of the cost involves making the trench and filling it back in, and this doesn t change much whether one material or another is used. The primary considerations should be how often repairs will be needed and how much those repairs will cost, looking decades down the road. The various materials perform quite differently depending upon their brittleness, environmental exposures, and loading conditions. No single material works best in all cases. How should infrastructure be managed to reduce water quality problems? Answer: In an ideal world, all unlined mains would be replaced or lined and all lead services would be replaced up to the residence. Given limited resources, a utility may need to consider a mix of solutions involving corrosion inhibitors, mains flushing, pipe rehabilitation and partial service line renewal. How can the condition of a water main be assessed? Answer: Techniques are available to perform a detailed, full-length scan of most types of water pipes, but utilities have not fully embraced these methods because of uncertainties about their benefits, and difficulties employing them within an operating system. Ongoing research is exploring how these (and less intrusive methods) might be used economically to provide better-informed main renewal decisions. When should trenchless renewal be used? Answer: The cost and disruptions associated with water main replacement programs may be greatly reduced through effective pipe rehabilitation and spot repairs, yet the water industry has been slow to adopt pipe rehabilitation as the primary means of renewal. The benefits of using the various lining systems within pipes of uncertain integrity are somewhat fuzzy, but cases of very successful large-scale programs exist. A current

xxvi Answers to Challenging Infrastructure Management Questions WaterRF project that marries condition assessment with rehabilitation may help overcome some of this industry reluctance. How does a utility build a case for a large infrastructure renewal program? Answer: By gathering the data and performing the technical analyses outlined in this report, a utility lays the foundation for its case, but convincing customers and policy makers of the necessity to spend money is never easy. To communicate program needs, to determine financing alternatives, and to sustain support through many years, a multidiscipline team with many skills, talents, approaches, and personalities is required. APPLICATIONS This report should be directly applicable to utilities in their current daily operations and capital investment planning. It also provides guidance to other reports where more detailed information is available.

CHAPTER 1 - INTRODUCTION The greatest infrastructure challenge facing public and private utilities today is a lack of adequate funding for asset assessment, maintenance, and renewal. Historically, much of our water infrastructure was paid for by land developers, and the cost of these green field systems was included in the price of the housing and other buildings. This allowed water and sewer rates to be kept relatively low, as long as these assets were in reasonably good condition. Now as the need to renew aging urban pipelines and other facilities has grown, funding has not kept pace. The result has been a large and growing backlog of infrastructure renewal needs. In 1999, the Water Research Foundation assembled a group of technical experts from across North America, in a one-day workshop in Reno. The objective was to develop guidelines for a project, initially entitled "Synthesis Document on Distribution System Infrastructure". The project had a small budget and an ambitious goal: provide utilities with practical guidelines for "what to renew, and how to renew it". When this project was first undertaken, the field of asset management was in its infancy and most utilities in the US were just starting to realize that aging infrastructure was a concern. Prior to this workshop, the Water Research Foundation had published about a dozen reports directed at infrastructure issues, but most addressed narrow, sometimes esoteric topics. The synthesis document was to make this research more accessible and understandable, providing a practical manual for managers and engineers. The study culminated in Distribution Infrastructure Management: Answers to Common Questions, (Ellison, et al., 2001). How to assess and renew pipelines was the primary focus. Pipelines represented the majority of utility assets, but were the least accessible for examination. Much of this pipeline infrastructure was decades old, and while most utility managers knew they still had time before leaks and breaks got out of hand, they also understood that good stewardship meant keeping the system in reasonably good shape, rather than passing problems on to the next generation. The experts gathered in Reno agreed without exception that effective data acquisition and data management were fundamental requirements for an effective infrastructure program. The first emphasis of the report was therefore the various tools and techniques to gather useful data. These tools included state-of-the-art leak detection, pipeline locating, and potholing techniques, and "cutting edge" technologies such as round-penetrating radar. Equally important was data management. Even utilities with good data generally had difficulties accessing and analyzing it. Drawings were stored in one place, soil reports in another, leak records somewhere else. Few utility managers understood the power of geographical information systems in transforming data into useful information. With data, asset analyses could begin, the condition of the network could be assessed, and replacement needs could be forecast. Using software developed by the Foundation, budgets for infrastructure renewal could be set. New tools for assessing the condition of individual pipelines were also discussed, including in-pipe non-destructive examination devices capable of scanning mains from end to end, detecting pitting in iron pipe and wire breaks in prestressed pipe. By using these tools, the condition of individual pipelines could be determined, their remaining lives estimated, and projects for renewal could be developed. The idea of using pipeline rehabilitation and other trenchless methods for infrastructure renewal was a fairly novel idea at the time. Few utilities in the US had used any method other than open-trench construction. Fewer still were willing to try alternative methods without guidance from an independent authority, such as the Research Foundation. The completed study 1

2 Answers to Challenging Infrastructure Management Questions provided the first authoritative comparison of more than one dozen renewal methods, including non-structural, semi-structural, and fully structural methods. The study also provided guidelines on how to manage a successful infrastructure program, including ways to garner political support, develop project budgets, and manage customer expectations. Much has changed in the dozen years since the publication of that earlier report. Awareness of infrastructure needs has increased, and asset management is now the norm, not the exception. Yet utilities still struggle with the same fundamental questions: How long will our pipelines last? Which pipes should be renewed? What are the best ways to renew our pipes? How much money is needed? This new report, Answers to Challenging Infrastructure Questions is an update of the earlier project, but with somewhat different emphases. Infrastructure research has exploded during the intervening decade, so while some of the original content has been retained, there is considerable new knowledge to help answer these fundamental questions. As before, the emphasis is on pipelines, but other distribution assets (tanks, pump stations, and plants) are also touched upon. PROJECT APPROACH Three sources provided the lists of issues and questions discussed in the current report: 1. The questions from the 2001 report were reviewed by both the Research Team and the Project Advisory Committee. Important questions were kept, but some were modified for editorial reasons. Admittedly, not all these questions are technically challenging, but they provide a basis for planning and managing an infrastructure program, which is a challenge. 2. An independent list of questions was developed at a project workshop attended by infrastructure experts and managers from several leading utilities from across the US. 3. A comprehensive review of Water Research Foundation reports was completed, and from this a list of general questions was derived and further discussed at another utility workshop. At a second workshop, infrastructure experts and leading utility managers vetted the list of questions, filling in gaps. The amount of research focused on these questions has increased several times over. Still, the difficulty remains in interpreting and synthesizing the research so it accessible and understandable for solving real-world, everyday problems. Some of the answers provided here are opinions rather than provable fact, but these opinions are informed by the research and provide practical and useful information. The most challenging infrastructure questions are NOT answered directly in this report, namely how can renewal be financed at reasonable levels, without over burdening customers; and how can public and political support be achieved and sustained, so a program can be implemented? These questions were repeated time and again in the workshops with utilities. While easy answers to these questions do not exist, the answers must begin with a technical

Chapter 1 - Introduction 3 analysis of the infrastructure and development of alternative solutions. It is hoped this report provides technical guidance for these tasks. Only by assembling the data, performing the assessments, and clearly communicating the results, can a utility answer the most challenging question, How do I get the money for what needs to be done? HOW BIG IS THE PROBLEM HOW WELL ARE WE KEEPING UP WITH OUR INFRASTRUCTURE? As a whole, we are probably doing about as well with belowground water pipelines as we are with the aboveground roads and other infrastructure perhaps not that well. In many areas of the US, deterioration of visible infrastructure is rather apparent. With buried infrastructure, the deterioration is not as obvious, so it could be more serious for that very reason. Pipeline problems may lay dormant until they manifest themselves with leaks and breaks. Water utilities in the US replace about 0.5 percent of their pipeline assets each year, with individual programs typically ranging from 0 to 1.5 percent per year (Stratus Consulting Inc., 1998, AWWA, 2011). At a rate of 0.5 percent, complete inventory replacement will take 200 years. Is such a turnover rate adequate? The answer is probably no, if we re talking about a long-term rate. Few in the industry believe the average pipe will last 200 years (although pipe life estimates can be rather long). The answer is yes, if we re talking about a short-term rate indeed, the pipes are holding with only occasional outages and community impacts. This replacement rate works because, on average, the pipes are still relatively young and break rates are still generally manageable. But as these pipes grow older, the break rates and the replacement rates will go up. When this will occur and how great the burden it will impose on customers are questions that few utilities can currently answer with confidence. Over the past 10 years, many studies have pointed to a large and growing infrastructure replacement deficit. The US Environmental Protection Agency s (EPA s) fourth national assessment of public water system infrastructure showed a total twenty-year capital improvement need of $335 billion. This estimate represents infrastructure projects necessary from 2007 through 2026. In constant dollars, this estimate has ballooned from the $200 billion estimate in its first report, in 1995. A much bigger number comes from AWWA s widely publicized report Buried No Longer (AWWA, 2012), which indicates that restoring existing water systems as they reach the end of their useful lives and expanding them to serve a growing population will cost at least $1 trillion over the next 25 years, if we are to maintain current levels of water service. This report goes on to say Delaying the investment can result in degrading water service, increasing water service disruptions, and increasing expenditures for emergency repairs. HOW DOES INFRASTRUCTURE AFFECT THE DISTRIBUTION SYSTEM? WaterRF Project #4109, Criteria for Optimized Distribution Systems (Friedman, et al., 2010) identified goals for the distribution system and grouped them into three categories: Hydraulics. The system should efficiently meet customer demands and have the ability of delivering required fire flows. Key metrics were identified as minimizing pressure fluctuations, meeting minimum pressure requirements, and avoiding surge events.

4 Answers to Challenging Infrastructure Management Questions Reliability. The system should be designed, operated, maintained, and renewed so that customer needs are reliably met and with no undue risks to the community. A key metric is the annual rate of main repairs ( break rate ). Keeping the break rate low, minimizes the cost, disruption, and various risks associated with main failures, including the risk of pathogen entry. Water Quality. The system should not affect the quality of water at the customer s tap in such a way as to make it unhealthful or distasteful. A key metric is to maintain disinfectant residuals within limits throughout all parts of the system. The deterioration of pipeline infrastructure negatively affects each of these goals. Although we tend to focus on reliability (main break rates) when talking about water main deterioration, renewal programs can be justified by improved hydraulics and better water quality. [Even mains that have never leaked warrant rehabilitation, if they are unlined cast-iron choked with tuberculation and sediment.] An overriding objective is accomplishing these goals within budgetary limits, without needless expense. WHAT ARE THE BENEFITS OF AN INFRASTRUCTURE ASSESSMENT AND RENEWAL PROGRAM? A well designed and managed program of infrastructure assessment and renewal helps a utility achieve these goals: Economy Work that is planned and well managed is more economical than work that is unplanned and chaotic. So, replacing a pipe, or making a repair during normal hours, before problems erupt, is inherently better than reacting to a crisis in the middle of the night. Moreover, proper infrastructure maintenance (e.g., the recoating of a steel water tank), prevents costly damage to the asset, extending the asset life. However, simply replacing an asset is not the solution, for replacing a sound asset, simply because it is old, is even less economical than waiting for problems to occur. The key to economy is knowing which asset to renew, when to do it, and how best to do the job. Water Quality Infrastructure renewal can directly improve the quality of delivered water, both aesthetically and from a sanitary perspective. When customers receive red or brown water from heavily corroded cast-iron mains, they certainly can t feel very good about the quality of water, or about the utility that serves it. They have a right to be concerned. Although the iron content that causes the water coloration is not a primary health issue, 1 the conditions that create the brown water can also deplete the chlorine residual and allow coliform regrowth. 1 Standards for iron concentrations are considered secondary because they address aesthetic qualities and are not aimed at health concerns. Discolored water can affect more than aesthetics, however, by staining laundry and plumbing fixtures.

Chapter 1 - Introduction 5 There are also serious water quality concerns caused by failing pipes. Every time a pipe is breached and then returned to service without super-chlorination and testing for bacteria, there is a risk that pathogens have entered the system. Because of the seriousness of this issue, it has been subject of several WaterRF projects (e.g., Project 4307, Effective Microbial Control for Main Breaks and Depressurization (on-going) and Project 2610, Practices to Prevent Microbiological Contamination of Water Mains, Pierson, et al., 2001). Customer Satisfaction Surveys have shown that customers can be fairly pleased with the results of infrastructure renewal programs, despite the temporary inconvenience and mess they create. Customers will perceive improved water quality, and appreciate the efforts of the utility to improve the system. They will also recognize efforts made to coordinate work with other public works projects, to schedule service interruptions at convenient times, and to minimize traffic tie-ups. Customers are never pleased with discolored water, uncoordinated work, unscheduled outages, and similar deficiencies they attribute to poor management. Improved Fire Low and Hydraulics In the older portions of many cities and towns, the available fire flows can be abysmal. Not only are the mains often undersized by current standards, but many are choked with tuberculation. 2 Six-inch mains can be narrowed to only two or three inches. Four-inch mains can appear completely plugged. These constrictions dramatically impact fire flows, and may also affect delivery pressures during peak demands. Heavily scaled pipe can make it impossible to add any new customers, impeding the redevelopment of inner cities. 3 WHY DID THE PIPE BREAK ON MAPLE STREET? WHAT ARE YOU DOING ABOUT IT? There are both technical and political answers to these questions, and both need to be formulated before the pipe breaks. A utility manager understands that water mains are in fact expected to break, occasionally. Planning a system where mains never break would require a great deal of money, and even then the goal could never be guaranteed. The failures of most mains are easily managed events, with minimal consequences. A common water main break should be no more remarkable than a pothole in the street, or a tree damaged in the wind. None of these are evidence of mismanagement, but because the main is out of sight and the break occurs without obvious cause, utilities receive increasing blame for their failures. To prepare the political answers to the questions above, the technical answers must be mastered. Knowledgeable critics will not accept that the break was an unpredictable and unforeseeable (an act of God). While there will always be randomness in these events, they re 2 Tuberculation refers to mineral and corrosion deposits that occur on the inside of unlined iron and steel pipes. Figure 4.1 illustrates. 3 Building Departments generally require fire flows certifications before they will issue building permits. When the current infrastructure cannot provide the needed flows, the developer s options are: (1) improve the mains (generally very expensive), (2) construct a costlier building (e.g., with fire sprinklers and/or more fire-resistive materials, or (3) abandon the project.

6 Answers to Challenging Infrastructure Management Questions also predictable and manageable. The political answers should clearly demonstrate that utility is proactively managing its system, replacing and rehabilitating infrastructure based on a longrange plan and established engineering criteria not just reacting to events. In fact, this answer should be communicated well before the main break on Maple Street and repeatedly. Acknowledging that mains are expected to break is not a free pass. There are some pipelines too important or too hazardous to allow to fail. For these mains, detailed assessments are prudent, including periodic field condition inspections and tests. Hopefully, these steps prevent disaster from happening, but if something unexpected does occur, at least the utility can justly claim it did everything feasible to prevent it. WHAT DOES THE FUTURE HOLD? Infrastructure management should not mean an overwhelming consumption of resources such that the infrastructure is managing the utility. Nor should it mean adequate delivery of service. Rather, infrastructure management entails the development of records, the analysis of systems, the evaluation of materials, and the timely renewal of facilities, such that the infrastructure efficiently and effectively performs its functions, without undue problems, costs, or risks. In 2001, when Distribution Infrastructure Management was published, the following expected developments were identified: Information systems that store, keep up-to-date, and analyze data for pipes, valves, meters, and other system components. Instrumentation systems that continuously monitor flows, pressures, customer consumption, leak noises, and corrosion activity at thousands of points in the system. Operating systems that continuously collect and process this information, alerting operators to suspicious events and potential problem areas. Assessment tools that accurately measure a pipeline s condition in place, allowing the utility to target the 1 or 2 percent that is defective, and leave in service the 98 to 99 percent that is merely old but still relatively good. Renewal techniques that restore structural integrity, improve water quality, minimize community impacts, and can be accomplished at significantly reduced costs. In the 12 years since publication of the predecessor report, a great deal of headway has been made in developing the systems and tools needed for effective distribution infrastructure management, but we are still a long ways from deploying these tools most effectively. With an eye to the future, good managers can create the practical applications, and develop a 21st Century water system through their day-to-day decisions.

CHAPTER 2 ASSET MANAGEMENT Asset management helps determine the need for infrastructure investments, taking into consideration customers service levels, community impacts, utility risks, and resources. Asset data are used to predict future failures, assess risks, set budgets, calculate financing requirements, and prioritize pipelines for detailed assessment or renewal. WHAT EXACTLY IS ASSET MANAGEMENT? WHERE CAN I LEARN ABOUT IT? Asset management encompasses many things, involves many systems, and includes many responsibilities: Asset management includes the systems that record the location, condition, and value of assets, including the assembly, storage, and retrieval of information about these assets. Asset management includes methods to analyze asset data so that intelligent decisions can be made regarding maintenance, rehabilitation, and replacement. Asset management also reflects the policies and procedures of the organization, in terms of customer service levels, investment priorities, and risk management strategies. For water utilities, asset management is business management. The primary business of a water utility is to capture, treat, and deliver water, and the planning, financing, design, construction, maintenance and operation of facilities and other assets is a large part of what utilities do. 4 The WaterRF has begun development of a Knowledge Portal on Asset Management which is available on the WaterRF website, with over 50 research reports related to asset management. The Knowledge Portal is intended to help synthesize information from the WaterRF and other sources into useful products for the water community. The Knowledge Portal will be updated routinely with new and improved knowledge. The WaterRF intends to provide practical approaches and materials that can be referenced to aid water utilities in planning asset management activities and in making the case for why such activities should be funded. SIMPLE (Sustainable Infrastructure Management Program Learning Environment is a website jointly funded by the WaterRF and the Water Environment Research Foundation (WERF) which provides guidelines, training, templates, and decision support tools to assist utilities in developing and optimizing their asset management programs, including a self-scoring questionnaire, SAM-GAP (Strategic Asset Management gap), that allow a utility to compare itself to the top 10 percent of US and Canadian Utilities. Figure 2.1 illustrates, for example, how the City of Portland, Oregon, Water Bureau, ranked in 12 key categories for 3 successive surveys. 4 McGraw Hill s Smart Market Report, Water Infrastructure Asset Management: Adopting Best Practices to Enable Better Investments (2013) provides 14 key business practices to focus on for improvement. 7

8 Answers to Challenging Infrastructure Management Questions Source: Portland Water Bureau Figure 2.1. SAM-GAP analysis example One size does not fit all. To effectively manage a system, a proscribed program need not be followed, and a complete inventory of asset data is not needed before making progress toward better management decisions. While the various asset management guidelines and manuals provide good information about how to develop an asset management program, the process of developing a system can be a journey of many small steps, where a utility finds its own way. HOW DO I PLAN FOR FUTURE INFRASTRUCTURE REPLACEMENT? The general process of planning an infrastructure program is illustrated in Figure 2.2. Data are collected and analyzed statistically. Risks are assessed. Where appropriate, field inspections are performed to better understand condition. The remaining lives of the assets are then estimated, which enables planning for infrastructure replacement. The process is circular as information is learned, additional analysis if performed, supporting better plans.

Chapter 2 Asset Management 9 Source: HDR Figure 2.2. Infrastructure renewal planning GIVEN LIMITED RESOURCES, WHAT DATA SHOULD I FOCUS ON FIRST? Asset data are needed, first and foremost. The size, location, age, material, and condition of each asset are desired. The first focus should be the high-consequence assets pipes and other facilities whose failures would create major problems for the utility and its customers. Regarding condition information, the most important information for pipes is the history of leaks and breaks this provides the least-expensive direct information about pipe condition. In response to a survey question by Kirmeyer et al. (1995) which posed the question What are your criteria for deciding whether a particular section of pipe is to be replaced, the overwhelming choice of respondents was the number of leaks or breaks. Repair history continues to be the most important and cost-effective means of predicting future breaks and ultimately, in determining which pipes to replace and when. Since pipes break for different reasons, it is important to record how the pipe failed. What component failed? Was it a main, a corporation stop, a service lateral, or a gasket? If the pipe cracked, was it circumferential, longitudinal, or did the bell split? Was there a rust hole? Each of these factors has different meanings. How much was the pipe leaking? This may be important in analyzing the benefits of the program or in refuting a property damage claim. How was the pipe repaired? Was a nipple inserted, a repair clamp used, or was it plugged with redwood? Did we get a sample for an examination or lab test? A pipe repair represents an opportunity to increase knowledge of the system without incurring substantial additional costs. Customers are already impacted, traffic control is set, and the pipe is exposed. A properly trained response crew requires only a few extra minutes to gather critical data that can be used to better understand the cause of this failure, support system-wide failure assessment, and potentially defend the utility against frivolous claims and lawsuits. Keep in mind that no one has perfect data, and analysis and decisions can be made while new and better data are gathered. Do what you can, as you can, with what you have and aim to

10 Answers to Challenging Infrastructure Management Questions continue to improve your level of practice. Do not get stuck on dogmatic compliance with someone s asset management structure. WHAT IS A LEAK? WHAT IS A BREAK? ARE TERMINOLOGY AND DATA CONVENTIONS HOLDING THE INDUSTRY BACK? Before we can efficiently share data and learn from each other s experiences, the industry must adopt common definitions for key terms. In most AWWA and Water Research Foundation publications, break is defined as any breech of the pipe barrel, and includes leaks, ruptures, and blow-outs. It also includes leaks at joints. It excludes failures on service laterals. Not surprisingly, this definition is not universal; a break certainly connotes a larger event than a leak. Following the AWWA convention, this report will generally use the term break but may sometimes use other terms for greater clarity. Some utilities distinguish between a catastrophic main repairs and a routine main repair, but these events are not always black-and-white there are many shades of gray. The distinction between a main repair that is damaging and one that is merely annoying may not be that important when it comes to assessing the condition of the system. Both types of failure can be indications of deteriorating pipe condition. 5 However, when determining the risk associated with a failure, there is a major difference. Another common terminology discrepancy exists between the definition of failure and a main repair. To avoid confusion, this report will generally use the term failure as the point when a utility determines that a pipe should be replaced (death). So if a pipe has a main repair, the asset has not failed. Rather failure will occur when a utility determines that the risk of keeping the pipe outweighs the cost of replacement and chooses to replace it. WHAT DATA SHOULD I BE COLLECTING RELATED TO REPAIRS? As a minimum, the following data should be recorded for each repair: date, location (ideally GPS coordinates or a unique asset identifier), pipe material, pipe diameter, break type, repair type, and crew time. Additionally, data about customer service impacts can be powerful for supporting future renewal investments. For example, if customers were put out of service, how many customers were affected, and what was the duration of the interruption. These observations are all important in understanding the performance of the system. Photos should be taken of the site, property damage, pipe failure, and completed repair. Examples of repair reports can be found in various reports, including Distribution Infrastructure Management (Ellison, et al., 2001). Project 4374, Main Breaks: Current Knowledge and Research Roadmap (in progress) will create a guidance manual for addressing water main breaks and it will include main break data collection protocols. Project 4372, Effective Organization and Component Analysis of Water Utility Leakage Data (in progress) has produced a Leak Repair Data Collection Guide that will be published in early 2014. The use of a GPS enabled laptop computer, tablet computer, or smart phone with an interactive form can support efficient and effective data collection procedures. Project #4369, Best Practices for Water Utility Legal Protection and Claims Management from Infrastructure Failure Events (in progress) will produce a best-practices guide 5 The Los Angeles Department of Water and Power uses the term blow out to denote any main failure that results in damage to more than 100 square feet of pavement.

Chapter 2 Asset Management 11 for water utilities for management of claims before, during, and after an infrastructure failure to provide prudent legal risk protection. The guide will apply to a wide variety of scenarios that water utilities encounter. WHAT OTHER DATA MAY BE USEFUL FOR DECISION MAKING? In addition to repair history, other valuable asset management data includes: Pipe attributes such as diameter, length, pipe material/type, class or wall thickness, manufacturer, and year of installation Aggressiveness of water (Chapter 4) Condition assessment data (Chapter 5) Records of complaints, particularly regarding pressure, color, taste, odor Geographical location (coordinates) of pipes 6 Locations and types of valves, fittings, services, hydrants and other appurtenances Topography Coating, lining, and cathodic protection information Soil information, including type of native soil, corrosivity parameters, and bedding conditions Locations where the pipe is occasionally or continuously submerged in groundwater Operational data are also important: Maintenance records showing when valves, meters, hydrants, and pumps were last serviced Flow and pressure data for calibrating your hydraulic model, which is a fundamental step in system analysis, and for determining where significant pressure fluctuations occur Water production, purchases, losses, and consumption This hydraulic information can sometimes point directly to areas in the system where service is substandard. Difficulties in calibrating the hydraulic model often lead to the discovery of system problems, such as heavy tuberculation or closed valves within the system. Areas of high head loss often indicate heavily scaled, corroded pipe. It s important to start with the data that are in hand and build from there, methodically converting old records to modern formats, supplementing this with field inspections, GPS-verified locations, and opportunistic data. A priority is to interview those with institutional knowledge, before the information is forever lost. WITH THESE DATA, CAN I PREDICT WHEN A PIPE WILL BREAK? It s impossible to predict with even modest certainty when any particular pipe will break, but we can estimate general system performance based on historic performance and other variables. The more break data we have, the better the prediction. 6 A georeference is preferred over locations that refer to street centerline or curb face, which can change when streets are widened and realigned.

12 Answers to Challenging Infrastructure Management Questions Because we know which factors influence pipe performance, many attempts have been made to predict pipe performance based on these factors. Within certain confidence limits, statistical models tell us when the first leak is expected to occur, when certain classes of pipes will be due for replacement, and whether problems are expected to increase or decrease over the next several years. Prediction of pipe performance has been an area of considerable research for over fifty years. Early statistical studies used simple regression analysis, testing whether a linear relationship exists between a dependent variable (typically the age of the pipe at first repair) and various independent variables (such as pipe diameter and soil resistivity). In this type of analysis, both quantitative and qualitative independent variables can be used, with the number of variables ranging from a few to perhaps as many as ten. 7 Models developed in the early 1980s by the Des Moines Water Works, the U.S. Environmental Protection Agency, and the Massachusetts Institute of Technology were modestly successful, explaining between 23 percent and 38 percent of the variation in the age at first break (O'Day et al. 1986). However, these models were of more interest academically than practically, since even the best of them left the majority of variation unexplained. There was also little consistency from one model to the next, undercutting their general credibility as prediction tools. 8 Part of the problem is the linearity; the data are not linear. Many pipes go several decades before significant problems occur, then failures can accelerate as pipe degradation reaches a critical stage in more and more areas. For other pipes, significant infant mortality is seen, where defective materials and poor installation problems show up early, but then diminish as these problems are fixed. No statistical models have been developed that work well universally. When working in hindsight, with a lot of data in hand, it is easy to get models that seem to work both valid ones and nonsensical ones, 9 but finding a model that works well across many systems has been elusive. A Water Research Foundation attempt to develop a predictive model failed (Grigg, 2007). Among the conclusions from that lesson were: Main break modeling is complex and requires trained modelers to develop and run the models. Each utility must use its own data to calibrate its model, and such efforts require statistical expertise and can be costly, even if data are available. Considerable effort is required to perform quality assurance on the data. Even when models are calibrated, confidence levels in the statistical estimates are often lower than needed to for credibility in justifying pipe renewal investments. Consistent results across various systems have not been achieved partly because data are inconsistent. From one system to the next, differences in definitions (confusion as to what constitutes a leak, a break, a failure, and the end of a service life, for instance) and differences in data quality often confound any attempts to analyze it. The other problem may be even more 7 An example of a qualitative variable is type of material. In a model, for instance, variable X may be assigned the value of 1, if the pipe is cast iron, and a 0, if non-cast iron. Likewise, variable Y may be assigned the value of 1, if AC, and 0 if not AC. Using this technique, any number of qualitative variables can be included. 8 In an extreme example, the same variable showed a positive influence in one EPA model, and a negative influence in another. 9 With regression analysis, correlations have been found between the stock market performance, the height of hemlines, the winner of the super bowl, and the winner of the presidential race. While these relationships and many other nonsensical relationships can be demonstrated statistically, there is no reason to believe that one variable influences the other.

Chapter 2 Asset Management 13 difficult to overcome the fact that no two systems are similar. Each system has a unique mix of materials, environments, ages, and stress conditions, so different variables have significance in different utilities. Management interventions can also play a part in making one utility s data different from another s. Ironically, such things as a main replacement or leak detection program may make a proactive utility appear to be more problematic in the near term. 10 Finding a single model that works well across the board has thus far been impossible. Even within a single system, the available data often will be incomplete and inconsistent. Significant changes in data management (e.g. computerized maintenance management systems and GIS), data collection standards, system acquisition and consolidation, proactive leak detection, system renewal and development rates, material standards, construction standards, and other advances contribute to a heterogeneous data set. The statistician doing the analysis needs to fully understand the nature of the data and account for how it has evolved over time. It is interesting to note which variables have been considered statistically significant by various researchers. Among the variables used to predict the age at first repair (break) are: 11 Soil resistivity, soil ph, and redox potential (Des Moines) Diameter, type of pipe, internal pressure, portion of pipe in highly corrosive soil, and development type 12 (USEPA, with similar result from MIT) Freezing days, rainfall deficit, 13 age class, 14 soil, joint type, and diameter (WaterRF Project No. 461) Material, diameter, soil, traffic, pipe location, 15 type of joints (Failnet, Cemagref, France) Material, diameter, soil, traffic, pipe location, pressure (AssetMaP, INSA, Lyon, France) Material, diameter, soil, traffic, pipe location, pressure, type of joints, burst type, pipe condition, (NTNU/SINTEF, Norway) Material, soil, vintage (Kleiner, NRC) There is one important area of agreement among nearly all statistical studies of main breaks: once a failure has occurred on a particular pipe, our ability to predict future failures on that pipe is markedly improved. Every study has shown that a pipe s history of problems, is by far the most significant predictor in forecasting future problems (Ellison et al., 2001). Knowledge of past pipe performance thus provides the key to predicting future breaks and leaks, 10 A proactive utility may seem to have more leaks (because they go out and find them) and shorter pipe lives (because they replace them regularly). 11 O Day, et al, 1986, Eisenbeis, Gauffre, and Saegrov, 2000, and Kleiner and Rajani, 1992. 12 Development type was classified as industrial or residential and may be an indirect measure of traffic loading on the pipe. 13 Rainfall deficit is defined as the amount that precipitation for the period in question has fallen short of normal. There are two explanations for the observation that more problems occur during droughts. (1) When the soil is excessively dry, it shrinks and holds the pipe more firmly in place, making it more susceptible to breakage when thermal contraction occurs. (2) Lack of precipitation means lack of snow cover, which helps insulate the pipe from extremely cold temperatures. 14 The installation period is generally more important than the age, due to differences in material specifications and construction techniques. Pipes installed in the early 1930s, for instance, have been found to perform significantly better than pipes installed in the 1950s. 15 I.e., under roadway or under pavement.

14 Answers to Challenging Infrastructure Management Questions setting budgets, and forecasting the overall health of the system. agreement are: Smaller diameter pipes break at an earlier age Pipes in more corrosive soils break sooner Other areas of general Can t We Use Artificial Intelligence to Figure This Out? There is promise that artificial intelligence can sort through data and find relationships that we mortals can miss. Sydney Water engaged NICTA (National Information and Communications Technology of Australia) to assist them in developing a machine learning algorithm, whereby the predictions improve as information is gathered. Using their standard modelling techniques, Sydney Water had been finding that only about 15 percent of the pipes identified for condition assessment are actually in poor condition (i.e., 85 percent were false positives). In 6 months of preliminary work, NICTA increased this hit rate to about 30 percent in one of the case-study areas - effectively doubling the number of poor pipes that were identified (NICTA, 2012). Sydney Water sees significant benefit in this work not only for better targeting of condition assessment expenditures, but also for identifying pipes that are still in good condition, allowing life extension at a known risk. The NICTA machine learning algorithm is non-parametric, meaning all variables are treated equally at the start, with few assumptions about the model structure. The model can accommodate as many variables as one cares to use, and can detect unsuspected failure causes, such as a bad batch of pipe or poor workmanship by one developer. This analysis has now been used on break data from multiple areas, and it appears that different factors dominate failures in different locations. This result is consistent with much of what we have been learning about the local idiosyncrasies of water system failures. HOW DO I STORE AND MANAGE THESE DATA? Until recently, managing data was not easy. With the large numbers of pipes, valves, hydrants, services and other items to track, the accounting job was immense. The historic records were voluminous, with thousands of work orders, construction drawings, as-built reports, and other documents. Much of the data was frequently lost and forgotten. Retrieving information was never easy, and when an appropriate record could be found, its physical condition was often deteriorated, and the archived images were often poor. The big turning point in data management was the adoption of Geographical Information Systems (GIS) and similar information management systems. With GIS, important data became readily accessed through a spatial reference. Information could be displayed geographically, and analyzed electronically. GIS also linked to scanned images of the historic records, making them readily accessible. Although developing a state-of-the-art GIS system can be very expensive, it can be accomplished incrementally, achieving some early results while keeping in mind how the system will expand as time goes on. 16 Project 3051, Building a Business Case for Geospatial 16 One utility, for instance, chose to start its GIS system by inputting gate books, the schematic maps that show valve locations and other valve information. The utility determined that up-to-date valve information was more

Chapter 2 Asset Management 15 Information Technology (Ancel, et al., 2006) provides case studies showing the benefits of an integrated GIS system. Spreadsheet templates are provided documenting the substantial financial benefits of mature systems. How Should Asset Data Be Organized? Just as we use hierarchical relationships to organize our computer files into directories and subdirectories, a structure is needed for the asset data. Additionally, systems need to be organized so that data can be exchanged and updated between various systems: GIS, Computerized Maintenance Management System (CMMS), financial and accounting (F&A), and Customer Information System (CIS). The general hierarchy of asset data is: System (e.g., water distribution, wastewater treatment, etc.) Facility (e.g., pump station) Asset (e.g., pump) Asset child (e.g., pump motor) Attributes (e.g., horsepower, manufacturer, installation date) This data structure can be varied as needed to accommodate different systems and different data bases. WaterRF Report 4187, Key Asset Data for Drinking Water Utilities (Oxenford, et al., 2012) provides guidance. HOW LONG WILL MY PIPES LAST? The average life expectancies of water mains are anywhere from 50 years to 200 years (or more), depending on whom you ask. The answers are variable, because conditions and materials are variable, and pipe age by itself is a poor predictor of pipe condition. The answers are also variable because the death of a pipe is not a definitive event. Unlike a person, a water pipe can be made to last almost indefinitely, as long as someone is willing to keep fixing it. Ultimately, answers are variable, because management strategies are variable. Different utilities choose to manage their systems differently, and as a result, their pipes have different life spans. A pipe lasts until a decision is made to replace, rather than repair. Many studies have shown that age by itself is a poor predictor of buried asset condition. Figure 2.3 provides a very good illustration of this. As part of assessing risk, direct or indirect condition assessment may be used to better understand the condition of a pipe, and thus assess the risk associated with that pipe. The application of risk assessment and risk management principles could do much to decrease the infrastructure funding gap. important to more people than any other information. Getting a gate book system up and running was also considered a manageable project.

16 Answers to Challenging Infrastructure Management Questions Source: Photos: Portland Water Bureau and a northeast U.S. water utility (used with permission). Figure 2.3. Contrasts in pipe deterioration. On left is a portion of cast iron pipe that was buried for over 100 years, with remarkably little discernable deterioration. The pipe on right was buried for only 30 years. How Do I Estimate Useful Life Expectancies? For the reasons discussed earlier, the development of accurate industry-wide performance and renewal forecasts has proven to be elusive. The problem is not a lack of analytical prowess but rather limitations in the quality, quantity, and consistency of data. Without universal data standards, it is difficult to leverage data across utilities. Also, differences in practices create differences in performance. Within a utility itself, the meaning of data may change over time, depending on who collected it and for what purpose. Even utilities with rigorous data standards experience changes which hinder accurate forecasting. Decades of reliable data are needed before the life expectancy of an asset can be estimated with any reasonable accuracy. While forecasting future infrastructure needs can be challenging, this does not mean it is not worth doing. Typically, buried pipes represent the largest portion of a utility s infrastructure portfolio and failing to develop and refine a long-term plan is rarely an option. Regular analysis and updates of a utility s infrastructure renewal needs will shed light on gaps in data collection standards that can then be filled to enhance the accuracy of future models. Ultimately, a utility needs to understand the limits of the data and the models, work to continuously improve, and factor known accuracy issues into long-term funding plans. Fortunately, infrastructure plans span decades, so there are ample opportunities to tweak them. Life-Prediction Models. Using past performance data, future performance can be predicted with moderate results. Three methods are described below where stochastic methods are used to forecast the longevity of pipelines: (1) asset class performance modeling, (2) Weibull failure modeling, and (3) LEYP modeling. Non-stochastic methods include: (1) deterministic modeling and (2) benchmarking. Using multiple methods increases confidence in the predictions.

Chapter 2 Asset Management 17 In applying each of these methods, a utility will need to select the criteria that help determine assets lives. This may involve policy discussions regarding economic objectives, levels of service, and tolerance for risks, as discussed later in this chapter. Asset Class Performance Modeling This method examines the performance of statistically relevant groups of pipes with similar risks asset classes. Once these asset classes are defined, their performance (in terms of annual repairs per 100 miles of pipe) is assessed and a trend line is generated to project future performance. Based on the risk of each asset class, a minimum acceptable performance level or band of performance is defined. The intersection of the performance trend and the minimum level of service defines the estimated life of the pipe within the asset class and used to forecast future infrastructure renewal needs. Figure 2.4. Example of performance modeling for two asset classes. In this case, the AC pipe inventory has been divided based on the slope of the ground. This analysis shows that soil creep is a likely cause of AC pipe breaks in this system. Figure 2.4 shows an example where the relationship between pipe age and leak repair rates has been analyzed for two asset classes. This particular case looks at how failures of asbestos cement pipe are affected by the slope of the ground. For pipes where the ground slope is greater than 5 percent, a very strong and statistically significant trend supports an hypothesis that slow creep of the ground eventually produces excessive strains, leading to pipe breaks. These breaks may also be influenced to some extent by concurrent deterioration of the pipe material. Where the slope is milder, the relationship between pipe age and break rates is less

18 Answers to Challenging Infrastructure Management Questions pronounced and less significant, indicating that the effect of the material deterioration is a minor factor. These trend lines can then be used to estimate the life expectancies of these two asset classes, but in order to do this, an acceptable level of performance must be defined. If the acceptable level of performance is 15 breaks/100 miles/year, for instance, the higher trend line says the average life expectancy in hilly areas is 48 years, whereas the lower trend line says that life expectancy in flatter terrain is much, much longer. In defining what an acceptable level of performance is, several factors need to be considered, including the cost of a break repair and other consequences of failure. The accuracy of these projections depends on our ability to define asset classes that represent distinct differences in risk and on the quality and quantity of the data. Success is measured by the strength of the relationship (the R-squared coefficient). In this example, age explains nearly 92 percent of the variation in break rates for one asset class, but only 27 percent of the variation for the other class. Age is thus a very important predictor of breaks for pipes where the ground slope is significant, but less important in flatter areas. In the flatter terrain areas, additional likelihood factors need to be explored. The asset classes which are selected need to reflect differences in materials, loadings, and environmental conditions that make sense from an engineering and materials science perspective. For instance, as discussed in Chapter 3, we know that pit-cast and spun-cast iron pipe are significantly different materials, so modeling them separately makes sense. Likewise, we know that small diameter pipes tend to break earlier than large diameter pipes, so dividing pipes into size classes makes sense. When developing asset classes, it is important to balance precision with data quality and quantity issues. If too many asset classes are generated, data sets will be statistically insignificant resulting in white noise, ultimately producing confusing and potentially conflicting results. Weibull Survival Modeling Weibull analysis has become a standard technique for analysis and forecasting of failures, with the advantage of providing accurate forecasts with relatively small data sets (Abernathy, 2006). Figure 2.5 shows the results of a Weibull analysis of a water distribution system serving approximately 160,000 people, with over 60 years of main repair data. This particular graph forecasts pipe failures (deaths), not breaks. For the purpose of this analysis, a pipe failure was defined as two or more breaks occurring in pipes of length 100 to 1,000 feet and three or more breaks in pipes of length greater than 1,000 feet. These failure criteria were based on the assumption that longer pipes are more likely to have breaks and replacement of longer pipes will be more costly. Pipes less than 100 feet in length were not modeled because failures in these pipes are rare and could skew the results. 17 Failure was not limited by a time period; breaks that occurred decades apart were given the same weight as breaks that were separated by only a few days. These assumptions were all considered conservative. In this case, the analysis shows the average life expectancy is about 230 years, with95-percent confidence limits of 185 and 285 years. 18 17 Pipes were as defined in the GIS, as the pipeline between two fittings. Thus a pipe often represented the water main serving a city block, but sometimes had other meanings. 18 These are the 50 percent values, when half the pipe has failed and have has survived.

Chapter 2 Asset Management 19 Figure 2.5. Example of Weibull failure modeling of a medium-sized water system In performing either asset class performance modeling or Weibull survival modeling, repairs directly attributable to third-party damage (i.e., dig-ins ) should be excluded as random events that can occur to any pipe regardless of age, loading, or condition. It is also important to clearly, and thoughtfully define what is a pipe or other asset. In some GIS systems, a pipe is defined as extending from intersection to intersection (essentially a City block) while in other systems, a pipe may merely extend from one fitting or valve to the next. Either of these definitions could produce both very short pipes and very long pipes, which need to be taken into account in the analysis. LEYP Modeling The Linear Extension of the Yule Process (LEYP) is a survival model that contains three distinct components (Renaud, et al., 2011). The first is similar to the Weibull distribution and is meant to account for aging. The second component, called the Yule Factor, is meant to model the notion that on average, the duration between each subsequent main repair decreases as the number of main repairs on a single pipe increases. For example, the duration between installation and the first main repair will be longer than the duration between the first and the second main repair. The duration between the second and third main repair will be even shorter (Figure 2.6). The third component, the Cox factor, is meant to simplify the equation and account for performance variations based on pipe characteristics.

20 Answers to Challenging Infrastructure Management Questions Figure 2.6. Illustration of the Yule effect. In this example from a medium-size utility, the second break on any given pipe occurs about 3000 days after the first, and the third occurs and 2300 days after the second. Thus failures accelerate as the deteriorated condition of the pipe reaches a critical state. The theories that make up the LEYP model are generally supported by engineering judgment and by main repair data. While the model has not been applied to as many systems or data sets as the other models discussed in this section, it may very well prove to be a superior approach to Weibull. Further testing is required to validate this model. A detailed documentation of the history of the model and its adaption for the water industry is included in Renaud, et al., 2011. Deterministic (Mechanistic) Models Those of us who are engineers were taught to calculate stresses from various loading conditions and determine safety factors from the expected strengths of the materials. When a pipeline is new, these safety factors for most loading conditions are likely 2 or more, but as deterioration weakens the material or if loading conditions have increased, the safety factor generally diminishes (per the second law of thermodynamics). The end of the pipe s life occurs when the safety factor falls to a level where the risk is no longer acceptable and it is replaced. For a low-consequence asset, a safety factor as low as 1.0 may be deemed adequate. For highconsequence assets, a minimum safety factor of 1.2 or more is prudent. The WaterRF has published several reports that provide guidance in developing these deterministic (also called mechanistic) predictions. Makar et al., (2005) provides information regarding when fractures are expected to occur in cast iron pipe. Rajani et al., (2011) includes a model for predicting the growth of corrosion pits in ductile iron pipe. Hu et al. (2012) provides a

Chapter 2 Asset Management 21 guidance manual for calculating safety factors for asbestos cement pipe, based on water quality, soil corrosivity, and other variables. Although these deterministic models may be satisfying to us engineers who want definitive answers, accurate modeling of degradation rates and loading changes are very difficult to obtain. The result has been that these deterministic models seldom predict real pipe failures practically. When predicting failures of small-diameter (lowconsequence) mains, where occasional are allowable, statistical models (regression, Weibull, or LEYP) will provide more accurate predictions. For the high-consequence mains where occasional failures are not an acceptable option, deterministic models may be the only real option, but they should generally be bolstered by condition assessment data, gathered from the asset in question. In the case of PVC pipe, on the other hand, Burn, et al., (2005) showed promising results in forecasting future failure events, based on the age of the pipe, and the normal operating stress levels. These models were derived using Weibull analysis of defects found within the materials, and the known relationships between crack development, defect size and defect spacing. A similar method was used by Davis, et al., (2007) to predict crack development in polyethylene pipe, but this was less useful, since most recorded failures of polyethylene pipe were attributed to either poorly made welds or third-party damage not crack growth. Moreover, the crack-growth model for HDPE pipe did not account for chemical degradation, which may be a significant factor in long-term performance. Benchmarking Opinions regarding pipe life expectancy can be found in many different studies and publications. Some of these opinions are based on statistical analysis of specific systems, while others are based on expert opinion and may apply more generally. Using these benchmark estimates to plan an infrastructure program works well if the system is relatively young and currently experiencing few failures. Table 2.1 shows a sampling of these opinions from various sources. Because pipe life expectancy can vary greatly depending on factors that may be highly localized, these figures should be used cautiously and conservatively. Study Anchorage, Alaska Asset Class Performance Eugene, Oregon Weibull Analysis Eugene, Oregon Table 2.1. Various pipe life expectancy benchmarks Asset Class Service Life (years) Low Range High Range Comments AC 125 170 Assumes break rate increases 3% per Pre-1965 75 150 year and pipe is replaced with break rates are between 50 and 200 per cast iron 100 miles per year (depending on the Post 1965 55 135 risk category and the defined service cast iron level for the pipe) Ductile Iron 105 180 All pipes 150+ 250+ Based on 60 years of break data and failure defined as two breaks on a pipe. 4 to 6 inch cast iron 130 200+ Definition of failure is 20 to 40 breaks per 100 miles per year (continued)

22 Answers to Challenging Infrastructure Management Questions Study Asset Class Performance Portland, Oregon Asset Class Performance Boulder, Colorado Weibull Analysis Seattle, Washington Weibull Analysis US EPA, Clean Water and Drinking Water Infrastructure Gap Analysis Report AWWA, Buried No Longer A Report on the Nation s Drinking Water Infrastructure Large Western US Utilities Table 2.1. Various pipe life expectancy benchmarks Asset Class 8 to 12 inch cast iron Pre 1950 cast iron Post 1951 cast iron Service Life (years) Low Range High Range Comments 150 200+ Definition of failure is 15 to 30 breaks per 100 miles per year > 200 years Definition of failure is two or more breaks in pipe segment as 150 years recorded in digital data base since 1977 All pipes 150 200 Four definitions of asset failure based on varying degrees of conservatism Most pipes > 200 years Definition of asset failure is conservative All pipes 60 95 Believed to be based on expert opinion rather than data analysis. Cast iron 115 Based on expert opinion rather Cast iron (lined) 75 100 than data analysis. Ductile 60 110 iron AC 75 105 PVC 70 Steel 95 PCCP 75 (Continued) These results illustrate several important points: There is no industry standard method of projecting life expectancies for a pipe, or for defining the service level where a pipe should be replaced. There s no common definition for pipe death. In some instances, data-driven analyses may forecast considerably longer service lives than published industry figures. This is because the data-driven analyses

Chapter 2 Asset Management 23 reflect local conditions, whereas the industry numbers are often guestimates intended to conservatively cover worse conditions. While the data-driven figures are based on documented criteria that may or may not be applicable for other utilities, the technical bases of the published industry figures are less clear. Other Sources of Information on Asset Life Prediction The WERF publication, Remaining Asset Life: A State Of The Art Review Strategic Asset Management and Communication, (Marlow et al., 2009) provides a comprehensive review of the bases for determining asset lives, and the statistical and physical assessment techniques that can be used. What Does Experience Tell us About the Useful Lives of Pipe? Are Expectations Increasing? Over the last decade, anecdotal evidence suggests that our estimates of pipe life spans are increasing, partly because failure rates have not escalated even while renewal rates have remained modest. The pipes have been getting older, yet failure rates are still manageable in most systems. One example is the Los Angeles Department of Water and Power (LADWP). Approximately 15 years ago, as part of Project 265 (Deb, et al., 1997) LADWP managers indicated that they expected their average mains to last only about 70 years. This was based on an analysis of the mains that had been replaced historically. Applying the KANEW model (an infrastructure planning data base program available through the WaterRF) showed that LADWP should replace pipes at a rate of 2.3 to 4.4 percent per year (see Table 2.2, later in this chapter). At the time, LADWP was replacing mains at a rate of only 0.5 percent far below this required rate. So what has happened in the last 15 years? Rather than accelerating, LADWP has actually slowed its main replacement program, largely because the annual number of leaks and breaks has been steadily declining, as shown in Figure 2.7, and finding pipes that have failed repeatedly (those that are candidates for replacement) has become increasingly difficult. The decline in LADWP break rates has several possible explanations and is at least partly attributable to a large-scale water main lining program. 19 LADWP managers now say that many of their older pipes are expected to last 150 years. With new ductile iron pipe, wrapped in polyethylene and backfilled with cement slurry, LADWP hopes for a 200-year average life. 19 Starting in the late 1980s and continuing into the early 2000s, LADWP had a large-scale main lining program, which likely deserves credit for much of the decline in breaks. At this point, virtually all unlined cast-iron mains have either been lined or replaced.

24 Answers to Challenging Infrastructure Management Questions Source: Los Angeles Department of Water and Power Figure 2.7. The downward trends in LADWP main leak and break rate 20 This example is simply anecdotal. During the last decades, other utilities have no doubt witnessed increasing failures (e.g., Figure 2.16) and may estimate shorter service lives for their mains. Whether the average pipe in the US has a life span of 70 years or 200 years (or somewhere in between) will determine how soon and severe the burden on utilities will be, and whether the industry s current renewal rates are on target. WHEN SHOULD A PIPE BE REPLACED? An old pipe, like an old car, can be repaired over and over again, but there s a point where repairing it is less attractive than replacing it. Occasionally, this decision point can be black and white. More commonly however, these decisions present themselves in shades of grey. Figure 2.8 shows graphically the traditional concept. The longer the pipe lasts, the more repairs are needed, and the frequency of these repairs increases. On the other hand, the longer the pipe life, the lower the capitalized cost. Adding the present value of the maintenance and capital costs together provides the total cost. The optimum point is where the total cost is lowest. 20 The LADWP definition of break is different from the AWWA definition. A LADWP break is a failure where more than 100 square feet of paving is replaced. An AWWA is much broader, including any breach of the main.

Chapter 2 Asset Management 25 Figure 2.8. The return on investment model for asset replacement Solving this financial problem might seem difficult, but Hu, et al., (2012) provides a simple solution. In the appendix of the Guidance Document provided with Long Term Performance of Asbestos Cement Pipe (WaterRF Project 4093), a mathematical proof is provided that shows the optimum replacement point is provided by Equation 2.1. Optimum Break Rate = [Main Replacement Cost] / [Average Repair Cost] x [Discount Rate] (2.1) For example, if the replacement cost is $250,000/1000 feet of pipe, the repair cost is $10,000 per repair, and the discount rate is 3 percent per year, the optimum replacement point occurs when the repair rate equals 0.75 repairs / 1000 feet / year (or 3 repairs in 1000 feet in 4 years). 21 This model, like any, is only as good as the assumptions that feed it. Water utilities generally have accurate estimates of hard unit costs (e.g. repair cost, rehabilitation cost, replacement cost), but the industry has struggled to develop reasonably accurate estimates of the other consequences of failure (the indirect and soft costs). This model also ignores other considerations, such as minimum levels of service, risk management, and infrastructure stewardship (concepts discussed below). Just as we often trade in an old car before the repair costs are greater than a new car payment, well-managed utilities often replace pipe well before economics dictate and the reasons are similar: safety, reliability, and image. Rules of Thumb/Trigger Points Rather than solving this financial problem repeatedly, many water utilities have developed rules of thumb or trigger points to guide their pipe replacement decisions. These are typically based on break rates over a defined period of time. Examples are: 2 breaks/2000 feet in 2 years or 3 breaks/500 feet in 5 years. Where the frequency of breaks on a particular water main exceeds one of these triggers, it is added to the list of replacement projects. Because 21 For the derivation of this equation and its assumptions, refer to Hu, et al., 2012.

26 Answers to Challenging Infrastructure Management Questions local factors have great influence on the costs of repairs and replacements, a utility should generally not adopt another utility s criterion. SHOULDN T WE CONSIDER OTHER COSTS? WHAT ABOUT THE TRIPLE BOTTOM LINE? Most US water utilities are publicly owned and therefore have an implied obligation to act in the best interests of their customer/owners. This includes minimizing both the direct costs incurred by the utility, but also the direct and indirect costs incurred by these customers. Triple bottom line refers to accounting for the economic, social, and environmental costs of infrastructure decisions and events. Among these triple bottom lines costs are: property damages paid by others (often through private insurance) impacts on businesses traffic delays impacts of water outages on customers cost of police, fire, and other emergency services intangible costs, including fire fighting risks and health risks Costs of Infrastructure Failure WaterRF Project 2607 (Cromwell, et al., 2003b) was among the first to tackle the subject of accounting for these indirect costs in water main breaks. For example, flood damage costs were estimated using a U.S. Army Corps of Engineers method and travel delay costs were estimated using transportation engineering methods. A method developed for the electrical utilities was used to estimate customer outage costs. Applying this cost model to 30 large-diameter pipe breaks, Gaewski and Blaha (2007) found that the societal costs were often greater than direct costs paid by the utility. They also found huge variability in costs. While the average cost was $1.7 million, the range was from $6,000 to $8.5 million quite a variance (the geometric mean was $0.5 million). They determined that the cost of failure was most influenced by the time required to find and close the valves. The diameter of the pipe was not a strong influencer on cost, but admittedly the data set was small and in all cases, the failures were of large-diameter pipes. In addition to the valve closure issue, the location of break also was a large factor in determining costs, with breaks in dense urban areas being costly. WHAT ABOUT THE VALUE OF MAINTAINING A REPUTATION FOR EXCELLENT SERVICE? Even after accounting for the indirect costs, there are other factors to be considered. Successful businesses in every field recognize that customers value many things that are quite intangible and very difficult to quantify objectively. Restaurants, for example, sell a great deal more than nutrition. These intangible values apply to water utilities as well. To be successful, a utility needs to present a professional image, respond promptly to problems, and treat customers well. The service they provide must be viewed as reliable, but not gold-plated. Maintaining a good reputation thus has value for which most customers are willing to pay something. Utilities may legitimately decide, for instance, to proactively replace mains and other

Chapter 2 Asset Management 27 assets, well before their economic values are depleted, as a means of keeping their customers satisfied with the service they are receiving. A utility that experiences frequent breaks and responds slowly to problems is viewed as ineffective and unsatisfactory, no matter how costeffective this operational strategy may be. Are Customers Really Willing to Pay for This Service? In several studies, customers have indicated a willingness to pay more for water, if the money increases system reliability. Using surveys and experiments, economists often calculate the economic value that customers are willing to pay for such intangibles. Project 4085, Assessing Customer Preferences and Willingness to Pay (Thacher, et al, 2011) provides a handbook for assessing customer preferences. The project estimated willingness-to-pay to avoid a substantial reduction in service levels due to water-pipe failures. The specific scenario valued was avoiding five outages over five years with an average outage length of eight hours. The conclusion: individuals were willing to pay a significant amount to avoid this scenario, about $10 per month on average. This lesson applies to more that service outages. There are reasons to believe that customers value a utility that not only keeps their break rates low, but manages risks, responds quickly to problems, completes its work safely and professionally, and treats customers respectfully and are willing to pay for these things. Economists can help in determining the monetary value of these attributes, or the utility may simply strive to achieve a balance between economy and service. One way of doing the latter, is to keep an eye of several key performance indicators, including the break rate. An earlier WaterRF study, Customer Acceptance of Water Main Structural Reliability (Damodaran, et al., 2005) developed a methodology utilities can use to assess customer perceptions, attitudes, and expectations for water system reliability, including their tolerance of service disruptions and construction impacts, and for their willingness to pay for expected levels of service. This information is useful for infrastructure decision-making process, along with the technical and economic analyses traditionally used. As part of this project, researchers queried more than 250 customers regarding their attitudes about main breaks and service interruptions. Among the findings were: 90 percent of respondents said that up to four service interruptions in 5 years would be acceptable Planned interruptions with appropriate notifications were judged more acceptable than unplanned, and shorter interruptions were more acceptable than longer ones 90 percent of respondents had experienced two or fewer interruptions in the last five years well within acceptable services levels How Do These Service Levels Compare to Industry Performance? The AWWA report, Benchmarking Performance Indicators for Water and Wastewater Utilities: Survey Date and Analyses Report (Lafferty and Lauer, 2005) includes information on the rate of service interruptions experienced by water utility customers, in different regions of the country and for different periods of disruption. Overall, the number of customers experiencing any unplanned water service outages is very low. Less than 0.3 percent of customers in any year experienced any unplanned outages, and 80 percent of these outages were 4 hours or less. The

28 Answers to Challenging Infrastructure Management Questions number of customers experiencing long outages (12 hours or greater) was very small (0.04 per 1000 customers). These data show that typical outage rates are within the acceptable limits for nearly all customers, and that expected service levels are being achieved. WHAT IS AN APPROPRIATE LEVEL OF SERVICE FOR MAIN REPAIR RATES? The appropriate level of service depends upon customer perceptions and local politics, as much as economics and engineering. Several utilities have found themselves accused of mismanagement when main breaks have caught the attention of the public, or when break rates are judged to be extraordinarily high, even if they are not. The report, Distribution System Performance Evaluation suggested a reasonable goal for main breaks for a system in North America is 25 to 30 per 100 miles per year (Deb, et al., 1995) Because this reflects current average performance in the US, the conclusion is this performance meets current customer expectations and is therefore defendable. A more recent study (Friedman, et al., 2010) recommended a break rate goal of no more than 15 per 100 miles per year, as a way of optimizing distribution system performance, including minimizing health risks and community impacts, in addition to effectively managing utility assets. For transmission mains and other critical pipelines where the consequences of failure are high, lower goals are appropriate. Indeed, some pipelines are too important or too hazardous to allow to fail. For these mains, periodic field condition assessment may be required, and the construction of redundant facilities may be advisable if the likelihood of failure is significant. It is important to remember that infrastructure problems can affect utilities and their customers in ways that are sometimes difficult to describe, much less quantify and compare, as illustrated in the following case study. LADWP Case Study How an Ordinary Main Break Became Catastrophic for the Utility In the summer of 2009, a temporary increase in the number of water main ruptures in Los Angeles caught national media attention, thanks to a very memorable picture (Figure 2.9). The mayor appointed a Blue Ribbon Commission to investigate the cause. Despite accusations by many that the system was mismanaged, the Los Angeles Department of Water and Power (LADWP) break rate (22/100 miles/year) was actually lower than the national average, and had been declining for some time (Figure 2.6), but changes in system operations had triggered a temporary rise in blow outs (an LADWP term for breaks that undermine more than 100 square feet of pavement). Not surprisingly, this period of high failure activity was soon followed by a period with lower activity.

Chapter 2 Asset Management 29 Source: Photo by Al Seib. Copyright 2009. Los Angeles Times. Reprinted with permission. Figure 2.9. The LADWP shot seen round the world The unfortunate consequence of the media attention was that the utility s reputation suffered, which impacted its ability to increase rates and re-invest in infrastructure. Similar main break stories have been experienced in other cities, including Washington DC, where the break rate has been 30 to 40 per 100 miles, per year still well below the economically optimum rates and well below rates in Europe. What Tools Can Assist in Determining an Appropriate Service Level? Project #4127, Benefit Cost Analysis Tool (Rose et al., 2009) provides an interactive, Web-based benefit-cost tool based on a 2006 UK Water Industry Research Ltd (UKWIR) tool. The tool is believed at the forefront benefit-cost analysis in the global water industry. A utility manager can either follow the process on a step-by-step basis or use the tool to obtain more detailed information on a particular aspect of the analysis. The tool is available on CD-ROM thru the Water Research Foundation, or on the SIMPLE website. Project #2848, Asset Management Planning and Reporting Options for Water Utilities (Matichich et al., 2005) developed asset management alternatives, including a Basic option, using service life concepts, a High-End option, in which weighted performance measures are used to guide decision-making, and a Strategic option, in which the impact of implementing strategies on system value over time are analyzed. All three options received strong overall marks by participating utilities, compared with no action. Data management challenges are much greater for the High-End and Strategic options. By studying the examples of outputs and the evaluations by the participating utilities and other materials contained in the report, utilities can gain insights into asset management programs and performance measures of value for their systems. How Can a Utility Know When the Time is Right for a Main Renewal? The answer depends on costs both to the utility and the public. Three strikes and out rule has been a popular rule for main replacement. Project 2870 s analysis (Damodaran, et al.,

30 Answers to Challenging Infrastructure Management Questions 2005) confirmed that with three breaks within a year, replacement is justified on the basis of a utility s internal costs alone. For a typical utility experiencing a system-wide break rate of 25 breaks per 100 miles per year, the three strikes scenario is about 60 times the average break rate. The results show that when external costs of customer disruption and traffic delay are included, the decision threshold for pipe renewal on a typical residential street might be on the order of 50 and 100 breaks per 100 miles per year. Customer costs were estimated based on a willingnessto-pay survey. How Does a Utility Estimate the Economic Values of the Bad Publicity, Customer Distress or Other Intangibles That Arise From a Main Break? Pairwise comparison is a technique where the relative importance of three or more items can be determined by comparing each pair of items successively, and summing the results. Using this technique, for instance, a utility might determine that customer distress is a more significant factor than traffic interruption, and has more value than a $20,000 repair. This technique can also be used to determine the weighting factors used in relative risk assessments (as discussed later in this chapter). Perhaps the simplest method of performing pairwise comparison is to list all the factors on both axis of a matrix. Then each pair of factors is compared. If the two factors are judged equal, both are given the score of 3. If one factor is slightly more important, it receives a score of 4 and the other is score at 2. And if the difference is great, one gets a score of 5 and the other 1. [The combined scores always equal 6.] After the scoring is completed for all pairs, the sums are totaled and the factors are ranked. HOW DO THE CONCEPTS OF RISK MANAGEMENT APPLY TO INFRASTRUCTURE RENEWAL DECISIONS? The return on investment model presented and discussed earlier (Figure 2.8) is based on the assumption that the costs of failure are both predictable and quantifiable and for routine asset replacement decisions this is a fairly reasonable assumption. The break of a 6-inch main next week on Elm Street is probably going to be similar to the break of a 6-inch main last week on Chestnut Street. But we also appreciate that a break on the busiest part of Main Street will entail different consequences and carries very different risks. Thus the risk of a break is not only associated with the likelihood of its occurrence, but also the consequences of its occurrence. Pipelines with higher risks merit more investment of time and resources. Risk Evaluation Concepts The risk associated with an event has two dimensions: the probability of the event and the consequence of event. To determine the degree of risk, both dimensions need to be assessed. The risk associated with a pipeline failure can be expressed as a mathematical equation: [Risk of Failure] = [Likelihood of Failure] x [Consequence of Failure] (2.2) Likelihood is a non-dimensional probability; therefore, risk and consequence have the same units. Consequence can sometimes be measured in economic costs. If it can be determined, for example, that there is a 1 percent chance that a pipeline will fail next year, and

Chapter 2 Asset Management 31 that the consequence of that failure would be a cost of $100,000, then the value of that risk would be $1,000 (0.01 x $100,000). To prevent this risk from occurring next year, a utility should be willing to spend up to $1,000. To prevent this risk from occurring over the next 20 years, up to $20,000 might be spent ($1,000 x 20). [For simplicity, this analysis assumes that the likelihood does not change and ignores the time-value of money.] Seldom do the probabilities and consequences of failure lend themselves to such easy computations. Although both likelihood and consequence can be the subject of statistical study, generally the data for a precise analysis are lacking. As a result, it is often helpful to depict relative likelihood and relative consequence as the two dimensions of a risk matrix, as shown in Figure 2.10. Figure 2.10. The two dimensions of risk For ease of analysis, these matrices are very often depicted as tables, with pipelines classified on each dimension as low, medium, and high, for instance. Numeric values can then be assigned and computations performed. The following matrix (Figure 2.11) shows an example of such a classification system, and a suggested response for pipelines that are classified in each of the resulting 9 categories. Figure 2.11. A relative risk assessment system As pipelines grow older, their likelihood of failure increases, but in many instances, the consequences of their failures also increase, due to greater urbanization, higher demands on the

32 Answers to Challenging Infrastructure Management Questions pipeline, higher property damage risks, and greater traffic loads on the street above. Thus as the system grows older, risks increase in both dimensions. The Consequence of Failure for Pipelines The consequences of failure are often thought to correlate with pipeline size. When larger pipelines fail, there is the potential for large releases of water (Figure 2.12), significant property damage, significant environmental damage, and significant disruption to water service. Very often, systems do not have redundancy for large pipelines; the loss of a large pipeline can result in complete loss of service or diminished service capacity to a large portion of the system. The damage caused by failure of a large pipeline is also not limited to physical or monetary damage the utility s reputation can also be damaged, which can be a serious issue. Source: Photo by Bill O Leary, Washington Post Figure 2.12. The consequences of failure for a 66-inch main near Washington, D.C. in 2008 For smaller pipelines, the consequences of failure are generally less significant. As a result, the traditional management of small mains involved a run-to-failure philosophy. Upon failure, these pipelines would be repaired repeatedly, until the projected cost of the repairs exceeded the cost of a new pipeline (O Day et al., 1986). Figure 2.13 shows the application of this concept of risk management, in terms of pipeline sizes.

Chapter 2 Asset Management 33 Figure 2.13. Relative Risk vs. Pipeline Size A caution: in assessing risks, there is often too much focus on pipe size. The pipe s material may have a more profound effect on consequences than the pipe s size. While all pipes can develop leaks, the fracturing of a pipe carries higher risks, and fracturing is generally associated with brittle materials (PCCP, cast iron, AC, and PVC) rather than materials that tend to fail in a ductile manner (steel and ductile iron). Additionally, where a pipe is located and how readily it is shut down can acutely affect costs. Using Relative Risks to Define Priorities Risk assessment concepts are helpful in determining which pipelines go to the top of the assessment and renewal lists. The most common technique for evaluating the risk of a pipeline is the weighted-score approach a technique familiar to most managers and engineers from various applications. 22 In this method, parameters representing both likelihood (i.e., break history, age, pressure, material type, soil corrosivity) and consequence (size, brittleness, damage potential, and system importance) are assigned weights based on a judgment about their contribution to risk. Then each pipe is given a score in each of these categories. The products of the weights and scores are then summed to yield a likelihood score and a consequence score. The product of these two scores yields a relative ranking of each critical pipe s risk. (More sophisticated variations or this technique are also available, including software developed specifically for piping networks. 23 ) Table 2.2 lists the factors commonly used in these exercises. 22 The results of Project 4451, recently selected, could be informative in generating more information on methods of identifying higher risk pipe and also in better understanding the possible consequences of failure. 23 Expert choice systems can also be employed. An expert choice approach using the Analytical Hierarchical Process derives the weights through a process of ranking the parameters relative to each others.

34 Answers to Challenging Infrastructure Management Questions Table 2.2. Factors Used in Assessing Pipe Failure Risk Variables Affecting Likelihood of Failure Leak or break history Pipe material Age Material type, strength Class or wall thickness Lining, coating and/or cathodic protection Diameter Seismic vulnerability (see Ch. 3) Environment Loading Soil corrosivity Groundwater Water aggressiveness Stray-current potential Pressure Surge and pressure cycles Ground stability, slope, seismic settlement Depth of bury / traffic Variables Affecting Consequence of Failure Pipe diameter Material ductility Potential for property damage Repair difficulty (access, depth, groundwater, shoring) Traffic conditions Business and other community impacts Potential for other environmental impacts Location and operability of valves Service to critical customers System criticality Pressure The basic weighted-score approach is simple and straightforward its drawbacks are its subjectivity 24 and relativity. When you re done, all you know is that some pipes are perceived to be more risky than others, but this is helpful as a means of prioritizing assets for further action. The next step might be in-situ testing or examination, but if sufficient evidence of risk exists, you may simply decide to rehabilitate or replace the pipe. This method is also helpful in defining the set of pipes that are considered to be low risk. These low-risk pipes, by definition, can endure a certain number of leaks or breaks before their condition warrants assessment. How many failures to allow is generally based on economic analyses, tempered by service-level and other considerations, as discussed earlier WHAT DOES "RISK MANAGEMENT" REALLY MEAN? Infrastructure asset management is a risk management program and utilities have used different methodologies to identify and differentiate varying risks associated with different assets. Project 4332, Integration of Cost of Failure with Asset Risk Management and Project 4451, Utility Risk Management Methodologies with Improved Triple Bottom Line Understanding of Pipe Failures (both currently underway) will develop additional knowledge and understanding 24 One way to make this method less subjective is to use the pairwise comparison method (as briefly described earlier) to determine weighting factors.

Chapter 2 Asset Management 35 of the range of approaches used by utilities to identify and quantify varying risks associated with buried assets. Project 4237, Best Management Practices for the Maintenance of Water Distribution Assets (also underway), is documenting the best management practices of leading utilities, including their approaches to risk. Project #2939, Risk Analysis Strategies for Credible and Defensible Utility Decisions (Pollard et al., 2007) reviewed the risk analysis strategies used by water utilities and developed a capability maturity model for risk management. The researchers found that risk management methodologies could help utilities define and identify factors that result in varying risks associated with their infrastructure. In general, risk assessment was viewed as an end rather than a means for innovation. Greater risk management advocacy within individual organizations was needed. There was little explicit expression of the risks that utilities are prepared to accept, whether the utilities have private, public, or corporate governance structures. The research team concluded that fostering a risk management culture within a water utility requires effective knowledge management, tenacity in addressing the underlying causes of incidents, and strong leadership. Further research that addresses risk management cultures within the sector is warranted. The compelling case for effective risk management should be used by water utilities as the core argument for moving towards an organizational structure that can be more strategic and forward-thinking. Seattle Public Utilities and Washington Suburban Sanitary Commission are viewed as leaders in using risk assessment and management in their infrastructure decisions. Appendix C provides information from these utilities. HOW DO I BUDGET FOR INFRASTRUCTURE REPLACEMENT? Several tools are available to set budgets for pipeline infrastructure renewal. The KANEW data base program, 25 originally demonstrated through Project 265, Quantifying Future Rehabilitation and Replacement Needs of Water Mains (Deb, et al., 1997), calculates a utility s annual needs for infrastructure renewal, based on the expected longevities of different classes of assets. A list of programs developed in Australia are documented in Project 462, Financial and Economic Optimization of Water Main Replacement Program (Cromwell, et al., 2003a), where utilities were compelled by national policy to develop comprehensive asset management plans that provide assurance of full cost recovery and sustainability. The Australian utilities first developed the Nessie curve (Figure 2.14). Similarly, a USEPA report (Stone, et al., 2002) provides an overview of software systems used in Europe for planning and prioritizing infrastructure renewal. A report to be published in 2013 (Project 4366, Addressing Revenue Gaps Through Improved Financial Practices and Effective Utility Management) will help utilities address the challenges of revenue gaps, which are exacerbated by rising customer expectations, declining water consumption, aging infrastructure. The project will also address the integration of utility finance functions with asset management, environmental justice, risk management, and other initiatives. Many of these programs start with assumptions regarding the average life expectancies of different asset classes and survival curves. When we say the expected life of a pipe is 100 years, we generally are talking about the median pipe in the class. Half of its cohort will have longer 25 While the KANEW program is still available through the WaterRF (and several utilities use it), it operates on an outdated version of Microsoft Access. AWWA offers a budgeting tool, Buried No Longer, available to utilities through their website.

36 Answers to Challenging Infrastructure Management Questions lives and half shorter. The KANEW model uses the Herz distribution, which is similar to Weibull, but assumes that no pipes will be replaced (no matter how bad) before they are at least 20 years old. KANEW then applies these assumptions to every pipe in the system and totals the results, producing the footage of pipe in each class that needs to be replaced in order to keep pace with the deterioration. Nessie curves (Figure 2.14) are graphical displays of the resulting budget forecast, named after its resemblance to the Loch Ness monster of lore. Source: Reprinted from Buried No Longer by permission. Copyright 2013 the American Water Works Association. Figure 2.14. Example of a Nessie curve. Nessie curves show estimated infrastructure investments needed to maintain service levels. Sensitivity analyses (Table 2.3) performed with KANEW indicate that changing the estimated life span by just 20 percent can double or halve the required near-term renewal rates. The KANEW method does not assess the condition of the network, nor does it predict how long pipes will last, it simply provides a method to plan for pipe renewal, using predictions regarding the life spans for certain classes of pipe.

Chapter 2 Asset Management 37 Table 2.3. Results of KANEW Analysis for Five Water Systems Required Short-Term Renewal Rates 26 System Optimistic Pessimistic Philadelphia Water Department 0.6% 1.2% Los Angeles Dept. of Water & Power 2.3% 4.4% Boston Water & Sewer Commission 2.0% 6.5% Fort Worth Water Department 0.3% Nottinghamshire Water System (Severn Trent Water) 1.5% 3.3% Source: Deb, et al., 1997 Forecasting future rehabilitation needs is an art as a well as a science. While we have good analytical tools, the answers they produce can diverge quite sharply, depending on what data, assumptions, and criteria are used. This means that a manager should apply sound judgment as well as the state-of-the art analyses, and repeat the analysis every 5 to 10 years taking into consideration how the break rate has changed. Project #4395, Selecting Methods for Projecting Life Cycle Asset Management Investment Needs (on going) will identify methods being used by water utilities in North America and Australia to estimate infrastructure funding needs, focusing on pipe, pump, and tank assets. Case studies will be used to illustrate the use of various tools. IF THE FUTURE PROGRAM APPEARS UNAFFORDABLE, WHAT CAN BE DONE? Some utilities who have done the analysis have concluded that there may be an unsustainable burden ahead. This is because water mains were often installed during development surges (Figure 2.15), and many fear an echo wave in pipeline failures as these assets grow old. Without a large monetary reserve or a growing rate base, this could overwhelm a utility s financial ability to address the problem. 26 Optimistic and pessimistic forecasts are based on the upper and lower limits of pipe-life expectations, as determined by the respective utilities. The required rate of renewal is the rate at which pipe reaches the end of its useful life.

38 Answers to Challenging Infrastructure Management Questions Is a large wave coming? Because these pipes are relatively young, the renewal needs are not yet significant, but with the majority of activity occurring in the period from 1950 through the 1970s, will the City have sufficient resources when these pipes begin to fail, or will the problem appear like a tsunami? Figure 2.15. Pipe installation history, Ventura, California In an ideal world, a large cash reserve would be built-up over many decades to enable a utility to deal with future increases in infrastructure costs; but in the real world, large reserves are nearly impossible to maintain for a public utility. An alternative strategy is infrastructure stewardship renewing a portion of the system every year, simply so the burdens on future generations are more manageable. This also keeps the community from looking like a construction zone. HOW WILL I KNOW IF THE RENEWAL LEVEL IS ADEQUATE? If your utility s annual break rate is flat or declining (Figure 2.6), you can sleep more soundly than if your break rate is escalating. However, the processes that influence failure and our ability to change these processes are measured over decades. Consider, for example, Figure 2.16. The rising trend in failures is well defined and statistically very significant. But then consider only the last 7 years. Since 2005, the trend has been sharply downward. Does this mean that the utility has made changes to reverse the trend, or is this similar to the natural variations seen in other periods. Only by looking backwards ten years from now can we make a technically sound determination, but those who manage this system today may already know the answer.

Chapter 2 Asset Management 39 Source: Metropolitan Utilities District, Omaha, Nebraska Figure 2.16. Example of a long-term break rate for a medium-sized city. While the 40- year trend is strong and clear, a reverse in the last seven years is seen. This could simply be natural variation (statistical noise) or the result of utility action. WHAT HAPPENS IF WE DO NOTHING? If nothing is done to renew or improve infrastructure, the results will be: Increasing operational risks Increasing liabilities Greater burdens on future customers Possible financial difficulties, possibly contributing to community decline But because of the long-term nature of the process, it may be decades before any of these problems become apparent. It is possible to do nothing for a long time (and retire quite happily). It s also possible to overreact, spending more money than necessary to renew infrastructure. Several utilities have discovered that when they do a thorough analysis, their infrastructure budgets go down, rather than up. AWWU Case Study: How Asset Management and Condition Assessment Reduced the Financial Burden Facing One Utility For the Anchorage Water and Wastewater Utility (AWWU), the development of an effective asset management information system was a long journey involving many steps, but the recent payback has been substantial. AWWU s information systems and related analysis have enabled utility managers to confidently scale back on long-range capital investments. Using

40 Answers to Challenging Infrastructure Management Questions statistical analysis to determine conservative, but realistic average service lives for mains, AWWU reduced its near-term renewal investments by 90 percent and peak future investments by nearly 40 percent. AWWU s asset management information system is remarkable for its integration, with the GIS, CMMS, CIS, and financial systems all operating on a common platform they don t just share information. The development of this system involved many steps and not always in the right direction. AWWU first began development of its GIS by digitizing large hardcopy maps where the history of the system had been recorded for many years. Like other atlas drawings, these maps were not spatially precise, but with the help of student interns equipped with high-quality GPS units, a reasonably accurate GIS has evolved over time. Source: AWWU Figure 2.17. Information value chain AWWU s CMMS uses the same data platform as its financial accounting system, but when integration between the GIS and CMMS was first attempted, the GIS system suffered. With the Information Technology (IT) Department leading the integration effort, engineering priorities were secondary, some GIS capabilities were disabled, and a labor-intensive, errorprone data entry process was needed to copy data from the CMMS to the GIS. These dark ages ended when the IT and engineering staffs began meeting weekly to solve problems utilizing the strengths of both departments. A data maintenance effort that once occupied 5 persons full-time was eventually reduced to a task requiring one person 10 minutes each week.

Chapter 2 Asset Management 41 AWWU has developed an information value chain pyramid (Figure 2.17) showing the ultimate goal for how their asset management information systems will be used for planning and management. In AWWU s estimation, only 10 of the 36 pyramid blocks have been completed, so considerable additional work is anticipated, but this has not prevented AWWU from obtaining significant benefits from their current systems. Using the historic break data from this system, several statistical methods were recently applied to estimate the expected service lives of individual pipe assets. These estimated service lives were based on analysis of acceptable service levels for individual neighborhoods and for the utility as a whole. Although conservative assumptions were applied, the analysis produced considerably longer estimated lives than had been used in previous analyses. Figure 2.18 shows the differences in the planning level estimates that resulted from the latest analysis. Because of this analysis, AWWU has been able to scale back their near-term capital expenditures, providing welcome relief to customers undergoing economic difficulties. Source: AWWU Figure 2.18. Comparison of planning-level asset renewal estimates, before and after statistical analysis of pipe longevity in the AWWU system HOW DO I SELECT PIPES FOR ASSESSMENT OR RENEWAL? Once criteria have been developed, selecting individual pipes for assessment or renewal is often done by plotting the information on a map. Although GIS has made this work easier, the concept of spatial analysis is older than the pipe itself. This is particularly useful in defining the limits of a project; if nearby pipes have shown a propensity for failure, they might be considered candidates for replacement as part of the same project (even if the number of failures has fallen short of the criterion for replacement). There are economies of scale in pipe condition assessment and construction projects, and if a pipe will likely need replacement within a few years, it should be included along with any nearby pipes that need replacement now. The spatial analysis may also indicate areas where the frequency of problems is inordinately high and further investigation is warranted. Such problems could be the result of corrosive soils, high pressures,

42 Answers to Challenging Infrastructure Management Questions surge problems, stray currents, material defects, cathodic protection problems, construction quality errors, unstable ground, or other criteria that may be local. GIS also enables spatial analysis of any kind of data not just leaks and breaks. Using this tool, pipeline deterioration might be detected through its effects on water pressure, color, odor, and taste, and these in turn can be detected through analysis of customer complaints and perceptions. GIS can also be used to display the results of chemical analyses from samples taken through out the system. By comparing these empirical data with results of water quality system modeling, an understanding of the changes occurring to the water, as it moves through the system may emerge. 27 Spatial analysis of water quality data can be particularly useful where aggressive water is a factor. If iron, lead, or asbestos concentrations or turbidity increase as the water moves through the system, this may indicate that the water is corroding the pipe. Spatial analysis of repairs is the most common method for determining which pipes need replacement, but with advances in in-situ assessment technology this may change. Instead of using repairs to determine when to replace, they may now be used to determine when to test, add anodes, or initiate better pressure management. For most communities, it s probably not cost effective to test every pipe, or even every old pipe. Most pipes within the system perform year after year, without problem or concern. However, a history of leaks or breaks, along with age, and other factors (such as pending street reconstruction) are issues that may make a pipe a candidate for testing. OTHER FACTORS TO CONSIDER IN SELECTING PIPES TO ASSESS AND RENEW Besides risk factors, other factors may spur the need to assess the condition of a pipe and/or schedule its renewal: Street reconstruction. Prior to street resurfacing, beautification, and other public works projects, an assessment or replacement of an old pipe may be warranted. Hydraulics. The need for replacement may be driven by undersized or heavily scaled pipes that provide insufficient fire flow and poor water pressure. Water quality improvements. Heavily scaled pipelines are a source of water quality complaints and concerns. While periodic flushing of these pipelines can help, it does not fully alleviate these problems (Chapter 4). Life extension. Cleaning and lining will arrest internal corrosion and increase the life expectancy of unlined cast iron and steel pipe (Chapter 6). HOW IMPORTANT ARE LEAK DATA AND LEAK MANAGEMENT? Leakage data are a measure of infrastructure health. Where leaks and leakage are increasing, the pipelines are deteriorating and risks are increasing. On the other hand, if leaks are sparse and leakage is low, the infrastructure may be in relatively good shape. Leaks, particularly small ones, don t always show on the surface, but finding small leaks may be an important way of preventing larger ones. For this reason, it is often advisable to actively search for leaks. Finding a leak early allows a utility to perform a repair when it s convenient, rather than when it s a crisis. 27 Commercially available hydraulic analysis programs are now capable of performing extended-time simulations of water quality changes in a distribution system.

Chapter 2 Asset Management 43 Finding a leak early is also an important way of conserving water, thereby reducing the cost of water production and water purchases. Water loss control programs and leakage management activities are therefore important utility activities. Water loss audits tell a manager whether significant problems exist and whether leak surveys and other interventions may be appropriate. Standard practices in this area have been evolving rapidly. The key recent references for water loss control programs and water audits are authored by the AWWA Water Loss Control Committee and are Manual M36: Water Audits and Loss Control Programs, 3 rd Edition, 2009, the AWWA web page called Water Loss Control Resource Community, and a June 2013 Journal AWWA article by Chastain-Howley et al, Water Loss: The North American Dataset. HOW DO I KNOW THAT I'M MANAGING MY SYSTEM EFFECTIVELY? This chapter has shown that there is no single index or method for gauging a system s condition. An overall assessment depends on employing various analytical techniques yielding different kinds of answers. Among the variables frequently used to gauge water infrastructure performance is: Break or leak frequency. A maximum of 15 to 30 breaks / 100 miles / year have been suggested by various sources as a reasonable goal. Renewal rates. 0.5 percent per year is regarded as the industry average. Many industry observers feel this is far too low. Renewal costs. The replacement of a 4-inch to 12-inch water main typically costs (in 2012 dollars) for between $100 and $500 per foot, depending on renewal method, size of pipe, project size, and locale. Benchmarking is frequently used, to make judgments regarding system condition, and appropriate renewal rates. For member agencies, the WaterRF and AWWA compile various performance indicators and makes them available through its WaterStats database. Information can also be obtained by contacting other utilities or various management consultants. The WATERiD knowledge data base allows for exchange of qualitative information, such as case studies, specifications, performance and cost information. Although it is interesting to see how a utility measures up to the industry as a whole or to similar utilities, these comparisons should be interpreted with extreme caution and should not be substituted for the analyses discussed elsewhere in this report. Each utility is different, and there are plenty of legitimate reasons why break rates, leakage rates, renewal rates, and costs will vary substantially from one utility to another. Probably the chief value of these benchmark comparisons is they furnish simple answers to the difficult questions asked by governing boards and the media. Other Sources of Information for System Performance Evaluation Project #804, Distribution System Performance Evaluation (Deb et al, 1995) determined primary criteria (adequacy, dependability, and efficiency) and developed measurement procedures and techniques. This study recommended national target levels for these measures and provided guidelines for assessing the overall condition of distribution systems to identify investment needs.

44 Answers to Challenging Infrastructure Management Questions Project #457, Guidance for Management of Distribution System Operation and Maintenance (Deb et al, 1997) provided guidance for distribution system managers to evaluate their O&M practices with respect to reliability and water quality. Project #4109, Criteria for Optimized Distribution Systems (Friedman et al., 2010) established optimization goals for leaks and breaks, pressure management, and disinfectant residual. The authors felt that if a utility met all three of these goals for their distribution system, the system would likely be optimized. This report also provides a four-step approach for continuous improvement. Step (1), compare utility data to numeric criteria for all three optimization topics. The software tools prepared for this project are used. Step (2), identify potential constraints to optimization verify optimized practices. Step (3), develop and implement an Optimization Action Plan for addressing the constraints and associated influence variables. Step (4), document and track ongoing performance to demonstrate continuous improvement leading toward optimization, or continued optimized performance. Besides the Break Rate and Leakage, What Other Metrics Can Be Used? Project 4187, Key Asset Data for Drinking Water and Wastewater Utilities Infrastructure (Oxenford, et al., 2012) discusses many ways to measure performance. Appendix C of that report shows how to calculate 22 different metrics for system performance, including: Break rate Pressure adequacy Infrastructure Leakage Index/leak rate Service interruptions Regulatory compliance Water quality indicators Water quality complaints Disinfectant residual concentration Lead, copper contaminant levels at the tap Customer complaints Project #2688, Investigation of Pipe Cleaning Methods (Ellison 2003) discusses measures for determining pipe cleanliness, before and after flushing projects (and similar interventions): Customer complaints (not very proactive) Measurements of turbidity, color, bulk iron from sampling stations (not from hydrants) HPC bacteria How Can I Compare Our Operations to Others? Through the AWWA Utility Benchmarking Survey, utilities can make benchmark comparisons of 63 high-level performance indicators in the areas of organizational development, business operations, customer relations, water operations, and wastewater operations. AWWA also conducts occasional benchmarking workshops. Data from surveys completed in 2005, 2005, 2007 and 2011 are currently available, and a 2012 survey is underway.

Chapter 2 Asset Management 45 Table 2.4 shows the metrics published in the 2011 survey that apply to Water Utilities (excludes Wastewater Operations). Table 2.4. Benchmarking Metrics Used in 2011 AWWA Survey of Members Customer Relations Business Operations Water Operations Customer Service Complaints Technical Quality Complaints Disruptions of Water Service Residential Cost of Water Service Customer Service Cost Billing Accuracy Service Affordability Stakeholder Outreach Index Debt Ratio System Renewal/ Replacement Rate (%) Return on Assets Cash Reserve Days Energy Consumption Efficiency for Water Triple Bottom-Line Index Drinking Water Compliance Rate (%) Distribution System Water Loss (%) Water Distribution System Integrity (per 100 miles of pipe) Operation & Maintenance Cost Ratios for Water ($) Planned Maintenance Ratio for Water (% per 100 miles of pipe) Current Water Demand Available Water Supply Portland Water Bureau Case Study: Developing the Tools and Processes to Measure Performance The Portland Water Bureau (PWB) sees value in applying benchmarking tools to measure its asset management performance and identify areas for improvements. By using such tools for several years, PWB believes it has improved customer service in measurable ways, while operating more efficiently, and with less risk exposure. One benchmarking tool, SAM-GAP, was discussed earlier, and Figure 2.1 showed the results of PWB s self-assessment surveys against other top-of-class utilities, based on approximately 150 questions related to business processes. PWB has also participated in the International Asset Management Performance Improvement Project, a joint effort by the International Water Association and the Water Services Association of Australia (IWA-WSAA). In this in-depth evaluation, responses were given for hundreds of business processes related to asset management. Both the capability (process development and documentation) and execution (coverage and frequency of application of the process) were considered. A majority of the utility participants had mature asset management programs; most of them are in Australia. The project evaluated current performance and recommended improvement initiatives. Figure 2.19 shows PWB s 2012 performance, showing that compared to other project participants, there s still plenty of room for improvement. Figure 2.20 shows PWB s performance in 2008 versus 2012, showing that considerable progress has been made. By measuring its performance against other top asset management utilities, PWB has successfully identified many ways in which to improve in key areas including water quality,

46 Answers to Challenging Infrastructure Management Questions customer service, financial health, infrastructure management, workforce and workplace excellence, conservation and sustainability. The result has been a more efficient and effective organization, exposed to lower risks, and providing measurably better service to its customers. By having measurements in key performance areas, PWB managers can confidently answer the questions, How are you doing?...and How do you know? Source: PWB Figure 2.19. Comparison of Portland Water Bureau with other project participants in International Asset Management Performance Improvement Project

Chapter 2 Asset Management 47 Source: PWB Figure 2.20. Comparison of Portland Water Bureau s 2008 and 2012 results in International Asset Management Performance Improvement Project

CHAPTER 3 MATERIAL PERFORMANCE AND CORROSION PROTECTION This chapter discusses the aging processes associated with each common type of water pipe and the failures they cause. This knowledge is helpful in estimating pipe longevity and assessing risks. Perhaps most importantly, by considering these factors in the design of new pipelines, improved life-cycle performance should be attainable. Additionally, the aging processes and maintenance of valves, hydrants, and tanks are briefly discussed. WHAT CAUSES PIPES TO FAIL? Simply stated, a pipe fails when the forces on the pipe exceed its remaining structural capacity. Structural stresses arise from internal pressure, pipe bending, temperature changes, and external loads. When first designed, pipes generally have minimum safety factors against failure ranging from 1.5 to 2.0 for calculated static loading conditions. As the materials deteriorate through corrosion and other aging processes, these safety factors decrease until a failure occurs. The good news is that there are several factors that help mitigate this loss of strength: Casting and corrosion allowances for cast iron and ductile iron pipes provide considerable initial reserve strength well above the required strengths Actual material tensile and bending strengths are generally above the minimums required by the standards Operating pressures for the vast majority (~90 percent) of pipes are less than the rated pressures of the pipes The bad news is that the design bases used for most pipes do not reflect how most pipes fail. Rather than bursting from excessive hoop stress, most pipes fail from either bending or slow crack growth. This occurs due to mechanisms not explicitly considered in their design, including dynamic loads (surge and cyclic fatigue) which can significantly impact brittle materials. WHAT ARE THE LOADS THAT FAIL PIPE? Internal Pressure While internal pressure is the governing design basis for most water pressure pipe, this type of failure is probably only the third or fourth most common. A study sponsored by the WaterRF and the US EPA which looked at leak and break data from six US water utilities (large and small) found that between 5 and 21 percent of pipe failed because internal pressure exceeded structural capacity (O'Day et al. 1986). Failures from excessive hoop stress exhibit longitudinal cracks or splits. Surge events (water hammer) also are often involved. Material fatigue may also play a role. 49

50 Answers to Challenging Infrastructure Management Questions Beam Bending The most common type of pipe failure is a circumferential crack or break and the cause is most commonly bending of the pipe like a beam. Buried pipes are generally designed to be fully supported, and many can handle only a small amount of bending deflection before breaking or leaking. This is particularly true of stiff, brittle materials, such as cast iron or asbestos cement. Regardless of material, there is a limit to how much deflection any pipe can safely withstand. Steel pipe can sustain considerable bending due to its ductile nature, but too much strain will crack and compromise cement mortar linings and coatings. HDPE pipe is the most forgiving. Bending of pipe is generally caused by differential soil settlement, which is frequently the result of inadequate pipe bedding or compaction. Other causes of bending are excessive vehicular loads, frost heaving, soil expansion, loss of soil material (e.g., due to sewer infiltration) and gross land movements. Pipe breaks are often associated with hilly terrain, particularly where clay soils are present. Widespread soil settlement caused by seismic shaking can lead to an overwhelming number of pipe breaks following major earthquakes, (as utilities in California and Japan can attest). Circumferential cracks are associated most often with small diameter pipes. The mechanics of beam bending explains this. The section modulus (bending modulus) increases by the third power of the diameter. A pipe with twice the diameter has eight times the bending strength. Larger diameter pipes also have thicker walls, giving them even more bending and axial strength. Large pipes can span over minor bedding problems that small pipes can t handle. Larger, stiffer pipes will also restrain the soil movements to a certain degree and encourage the soil to flow around the pipe. A less stiff pipe will be forced to move with the ground, resulting in damage, unless it is flexible enough to accommodate the movement. Temperature Structurally sound, buried water pipes should virtually never fail due to thermal stresses alone, but there s no question that cold temperatures contribute significantly to pipe breaks. A disproportionate number of problems with cast-iron pipes occur when the weather is cold. The WaterRF/EPA study previously cited found that between one-third and one-half of all breaks in Philadelphia, Denver, and New York occurred in the three winter months. Several explanations for this behavior have been offered, but most likely the breaks are mostly caused by pre-existing bending, corrosion, or other problems, which are exacerbated by the cold-temperature contractions of the pipe. The cold increases the axial stresses and triggers an event that would likely have occurred eventually. For asbestos cement pipes, the season breakage trend can be opposite. Drying of the soils results in shrinkage of expansive clays, and loss of support, causing or triggering breaks. High demands and associated transient pressures (surges) may also contribute to breakage spikes in dry, hot summer months. This behavior has also been seen in cast-iron pipe.

Chapter 3 Material Performance and Corrosion Protection 51 External Loading Pipes resist external loads in two very different ways. Rigid pipes, such as concrete, asbestos cement, and cast iron, rely on the strength of the pipe to pass loads from above the pipe to the soil below. Because these pipes are brittle, very little ring deflection can be accommodated. Flexible pipes, on the other hand, such as plastic, steel, and ductile iron, can accommodate considerable ring deflection. As these pipes deform, taking on a slightly oval shape, the sides of the pipe push outwards. As the sides push out, the soil pushes back, which helps resist the loads. In this manner, relatively thin-walled pipe can sustain relatively large loads without collapsing provided that the backfill on the sides of the pipe is well compacted. Pipes that fail from excessive external loading will crack or break either circumferentially or longitudinally, depending on whether excessive beam bending or excessive ring deflection occurs. Problems will often occur after a pipe has been depressurized and then returned to service. Usually internal pressure is sufficient to resist the external loading. As with other failure modes, corrosion is often a contributing factor to external loading failures. When the depth of burial is shallow, the pipe will be more affected by traffic and similar surcharge loadings. At least 3 feet of cover is a common requirement for pipes that are 16-inches in diameter and smaller. For larger pipes, greater burial depths may be desirable. Shallow pipes are also more vulnerable to damage from others during the installation of the gas, electric and telecommunication service lines, which are often bored across the streets. Fatigue Fatigue likely plays an overlooked role in the initiation and propagation of cracks in brittle pipe materials. Pressure cycles and traffic loadings can be sources of fatigue loadings. While pump starts and stops are obvious causes of pressure cycles, diurnal pressure fluctuations throughout the system may also lead to failures (Bardet, et al., 2010). Although fatigue is described as a load, it more properly is an aging process involving the progressive and localized accumulation of structural damage through cyclic loading, even when total stresses are well less than the yield and ultimate stress limits for the material. Fatigue begins with dislocation movements, which eventually form slip bands that nucleate to form short cracks. Like corrosion, fatigue damage does not recover when the stresses and cycling are removed or stop. The material is permanently degraded. WHAT ARE THE AGING PROCESSES ASSOCIATED WITH WATER PIPES? Table 3.1 summarizes the aging processes and resulting typical failures that result, for common water main materials.

52 Answers to Challenging Infrastructure Management Questions Table 3.1. Summary of Water Pipe Aging and Failure Processes Pipe Material Common Aging Processes Common Failure Modes Cast iron Ductile iron Steel Internal electro chemical corrosion External galvanic and electrochemical corrosion Ground movement 28 Fatigue Internal electro chemical corrosion External galvanic and electrochemical corrosion Ground movement Internal electrochemical corrosion External galvanic and electrochemical corrosion General Pitting Stray-current corrosion Rust holes or other leaks Bursts (longitudinal) Beam breaks (circumferential) Joint and service tap leaks Rust holes or other leaks Bursts (longitudinal) Beam breaks (circumferential) Joint and service tap leaks Rust holes or other leaks Bursts (longitudinal) Joint and service tap leaks Polyvinyl Chloride Polyethylene Asbestos Cement Concrete Cylinder Pipe (nonprestressed) Concrete Cylinder Pipe (prestressed) Slow crack growth Long-term creep Material degradation Slow crack growth Long-term creep Soft water corrosion (internal and external) Sulfate corrosion (external) Ground movement Loss of free lime from linings & coatings External sulfate corrosion External carbonation Corrosion of reinforcement Corrosion of steel cylinder Corrosion / breakage of prestressing wires Hydrogen embrittlement of prestressing wires Brittle fractures Third-party damage Joint and service tap leaks Third-party damage Poor welds, including service taps Brittle fractures (rare) Bursts (longitudinal) Breaks (circumferential) Leakage at joints caused by bad mortar or workmanship Pipe rupture (rare) Cylinder leakage (rare) Pipe rupture Leakage at joints caused by bad mortar or workmanship 28 While ground movement is not an aging process, per se, it can be age-related. The accumulation of imperceptible movements over many years can result in failure, particularly of highly brittle materials like cast iron and asbestos cement..

Chapter 3 Material Performance and Corrosion Protection 53 Iron Pipe Aging The development of modern water systems owes much to cast iron pipe. Although cast iron pipe has been used for nearly four centuries, it became widely accepted as modern systems started to develop, about 150 years ago. Cast and ductile iron constitute the majority of water main pipe in the ground in the United States. Under the right circumstances, iron pipe performance can be phenomenal a prime example is a pipe in Versailles, France, commissioned by King Louis the XIV, that is reportedly still in use today. It is not unusual to find pipe that is 100 to 150 years old in the older portions of many systems. However, many of today s water pipeline infrastructure problems are due to cast iron. Cast iron is involved in the majority of pipe breaks and has the highest rate of failures. Cast iron is a brittle material, capable of tolerating little movement without breaking. It is subject to galvanic corrosion and electrochemical corrosion. An historic problem in many systems has been the use of leadite joint material. 29 Unlined cast-iron also is the material most prone to tuberculation and its associated flow and water quality problems. Casting defects were a major problem with very old pipe. The earliest pipes were cast in two horizontal molds, then joined together and baked. This resulted in uneven wall thicknesses and the inclusion of many impurities. Pipe segments were also only 4 to 5 feet in length. Starting around 1850, pit casting was introduced, in which the pipe was cast vertically. This produced more uniform wall thicknesses and fewer impurities within the pipe wall. The next major improvement occurred in the 1930s, when centrifugal casting became widespread. 30 This method produced much greater uniformity and many fewer defects. By consolidating the material, centrifugal casting produced a denser material, with less porosity and voids, and smaller graphite flakes an inherently stronger material. These and other improvements, over the last 150 years, have taken the tensile strength of iron pipe from about 20,000 psi to 60,000 psi. These improvements have not always resulted in longer-lasting pipe. With improved manufacturing processes came reduced safety factors and thinner pipe walls. This resulted in less allowance for corrosion. Figure 3.1 illustrates how the minimum wall thicknesses of iron pipe markedly decreased; this example is for 36-inch diameter pipe. 29 Leadite was a brand name of a sulfur-based substitute for lead joint material widely used from the 1910s through the 1950s. The molten material expanded while it cooled, making it easier to apply. The material also expands when wet. This expansion has often cracked pipe bells in otherwise good pipe. 30 Centrifugal casting as the means of manufacturing cast iron pipe became widespread in the 1930s, but the process was developed in the late teens, patented in 1916 as the DeLavaud process, and imported to the US in approximately 1921 when US Pipe purchased the right to make pipe by this method. Although spun cast pipe became increasingly more common, some amounts of pit cast pipe were manufactured in the US into the 1950s, the last pit cast pipe may have been made as late as 1969.

54 Answers to Challenging Infrastructure Management Questions Figure 3.1. Minimum wall thicknesses for 36-inch iron pipe. Minimum pipe wall thicknesses for iron pipe shrank dramatically as manufacturing methods improved. With iron pipes, the aging process is well recognized. 31 Aging generally occurs through corrosion, which generally takes the form of pitting. These pits can result in holes in the pipe, and leakage. However, leakage does not always occur, or occur right away when pits completely penetrate the iron. Often the water is held back by scale, mortar lining, and graphite. 32 Figure 3.2 shows an example of a pitted ductile iron pipe which has been grit blasted and painted for visual clarity. Source: Photo courtesy of PICA Corporation Figure 3.2. One-inch diameter through hole revealed by grit blasting 6-inch ductile iron pipe Corrosion failures of pitted iron pipes occur from three general mechanisms: 1. Rust hole or blow out. A pit penetrates the pipe and grows sufficiently large for leakage to occur. 31 See Appendix A for a discussion about galvanic and electrochemical corrosion processes. 32 When iron leaches out of cast iron and ductile iron pipe, graphite is generally left behind, with little strength. Only when this graphite is removed through grit blasting will the extent of deterioration be known.

Chapter 3 Material Performance and Corrosion Protection 55 2. Longitudinal Split. Pitting weakens a large enough portion of the pipe that it splits longitudinally. Longitudinal splits can also occur where general corrosion has weakened the pipe so that hoop strength is less than hoop stress. 3. Circumferential crack. The pipe is sufficiently weakened that bending or axial stresses cause a circumferential fracture. In the first two cases, internal pressure is a contributing factor higher pressures increase the likelihood of failure. In the third case, ground movement is often a contributing factor, with failures sometimes triggered by colder-than-normal water (axial contraction). Pipe bending from ground movement can also cause failures when corrosion is absent. Ductile Iron vs. Cast Iron The chief difference between ductile iron and cast iron is the form of carbon within the metal matrix. Rather than the graphite flakes found in cast iron, carbon in ductile iron is formed into round nodules. This form does not tend to propagate cracks, making the material much less brittle. Because of this, ductile iron is less prone to longitudinal or circumferential cracking (Cases 2 and 3). However, when equally unprotected, both types of pipe are equally vulnerable to rust-hole failures. 33 Corrosion Pit Growth Figure 3.3 shows the expected rate of pit growth for unprotected ductile iron pipe in moderately corrosive soils, based on analysis by Rajani, et al. (2011). The data from many studies were used to develop these curves, which indicate that external corrosion of buried ductile pipe is a slowing process; the products of corrosion tend to protect the metal from further oxidation. Source: Rajani et al. 2011 Figure 3.3. Predicted pit growth for ductile iron pipe in moderately corrosive soil 33 Romer and Bell (2005) determined that in practical terms, corrosion of ductile iron, cast iron and steel occurs at roughly equal rates. Although the nodular form of carbon may impede corrosion somewhat, the difference is not believed to be significant. Nodular carbon is thought by some to impede corrosion by offering a smaller cathodic surface and less of a path for electrolyte penetration. Rajani, et al (2011) found that corrosion of ductile iron is initially faster than cast iron, but slows more quickly.

56 Answers to Challenging Infrastructure Management Questions Although corrosion is a well understood electrochemical process, natural variations in soil conditions, the possible influence of imported bedding, and temporal variations in weather and groundwater levels cause considerable variability in corrosion rates. Rajani used fuzzy logic to estimate the pit growth rate function shown in this model. This pit growth model explains much of the variations in failure rates that utilities experience with iron pipes. Figure 3.4 provides an illustration. According to this model, an unprotected pipe, with a 7.5 mm (0.3-inch) thick wall, installed in moderately corrosive soil (figure on left) will likely be penetrated by pits in about 45 years, but penetration could take as little as 25 years and as much as 120 years. If a thicker, 10 mm (0.4-inch) pipe were installed, pit penetration could occur in about 75 years, but may not occur for hundreds of years. By performing this analysis for different classes and different diameters of pipe, Rajani, et al., showed that pit penetration in moderately corrosive soil can occur in as little as 11 years (6-inch diameter, Class 50 pipe) and as much as 615 years (12-inch diameter, Class 56 pipe). 0.3-inch (7.5 mm) Thick Pipe 0.4-inch (10 mm) Thick Pipe Adapted from Rajani et al. 2011 Figure 3.4. The effects of pit growth for ductile iron pipe in moderately corrosive soil Although this model was developed specifically for ductile iron pipe, the following observations are equally applicable to cast iron and steel pipe, where the corrosion processes are similar: Unprotected thin-walled pipe can begin failing in a short amount of time Extra wall thickness can extend pipe longevity by many decades (e.g., using Class 55 ductile iron in lieu of Class 52) Because smaller diameter pipes are thinner, they will tend to fail sooner than larger diameter pipes Corrosion protection is more important for higher-strength, more uniform materials with lower factors of safety, because the tolerances for corrosion will be smaller

Chapter 3 Material Performance and Corrosion Protection 57 Should Ductile Iron Pipe be Wrapped? Although research from the Ductile Iron Pipe Research Association as well as the preceding discussion suggest that wrapping is not needed if the pipe is buried in relatively noncorrosive soils, in the opinion of the research team, unprotected metal should never be buried. The cost of wrapping the pipe likely adds little to the overall cost of the project, and has the potential of greatly extending the service life. AWWA Manual M42 recommends the use of 8 mil low-density polyethylene, or 4 mil high-density, cross-laminated polyethylene encasement as an economical, effective method of corrosion protection. This membrane serves several functions: (1) it insulates the pipe from the soil, (2) it limits the amount of electrolyte exposed to the pipe, (3) it retards the diffusion of oxygen to the surface, and (4) it provides a more uniform environment for the pipe. Even if soil analysis indicates non-corrosive soils, omitting this low-cost protection would seem foolish. At a small added cost, the membrane provides a safety factor that might not otherwise exist. In External Corrosion and Corrosion Control of Buried Water Mains, Romer and Bell observed in 2005, the causes of corrosion are known, but damage continues throughout in the water industry, with the placement of unprotected metal pipe in the ground. The problem of external water main corrosion is deferred to future generations. The asphaltic coating that is factory applied to most ductile iron pipe in the US provides very little corrosion protection and is largely intended to provide a finished appearance to the pipe. Unfortunately, it also may discourage the use of other, more effective coating materials. It must be noted that the use of wrapping does not guarantee success. Whenever an electrolyte barrier is used, imperfections ( holidays ) will probably exist, and corrosion will sometimes concentrate at these imperfections. Particularly when the process is galvanic (i.e., involving two dissimilar metals), the corrosion can occur rapidly. Where copper service lines are connected to a poly-wrapped iron pipe, for instance, corrosion can concentrate at the small holiday areas where the main is exposed to the soil and can bore holes relatively quickly through the pipe. Contrast this to an unprotected main, where the whole pipe is exposed to the soil. In this latter case, corrosion is more diffuse, so it may take more time before a leak occurs, but the whole main is being corroded the overall damage will be greater. The recommended solution is to electrically isolate copper services from iron main, using dielectric corporation stops or insulating bushings 34, as well as to wrap the iron pipe. In highly corrosive soils, particularly where groundwater is shallow and fluctuates, other corrosion protection alternatives may be needed or non-corroding pipe. Even very well wrapped pipes have experienced early failures in such severe conditions. Is Stainless Steel a Good Alternative, Particularly for Buried Bolts and Nuts? Uncoated stainless steel may work, but may not. It s probably not the best choice for buried hardware. Stainless steel contains a relatively high amount of chromium which reacts with oxygen to form a protective coating that resists corrosion. Often in buried or submerged applications, there will be insufficient oxygen to provide this protection. When a bolted connection is tightened, the protective coating can be damaged and if oxygen is not present, the coating will fail to reform. If water penetrates the connection and stagnates, galvanic corrosion 34 When using an insulating bushing, be sure to select one with an adequate pressure rating and safety factor. These bushings have themselves been a source of failure.

58 Answers to Challenging Infrastructure Management Questions can result from differences between the electrolyte inside and outside the crevices. Stainless steel bolts are particularly susceptible to corrosion in these situations. If chloride or chlorine is present, stress corrosion cracking can also occur with stainless steel. Even if the stainless steel does not corrode, it is cathodic to the iron or mild steel pieces that it is joining together and thus can promote corrosion of these items. Rather than stainless steel, Romer and Bell (2005) recommended that buried connection hardware be wrapped with wax tape per AWWA C217. With a good coating system, less expensive carbon steel bolts and nuts can be used, which reduces the chances of galvanic or stress corrosion. Some owners provide additional protection by encasing the completed tapewrapped assembly in polyethylene sheets. Should Ductile Iron Pipe be Coated and/or Cathodically Protected? Cathodic protection has been successfully used on ductile iron pipe for a number of years with polyethylene encasement; but a bonded coating is generally preferred for better electrical isolation and the avoidance of shielding. 35 Bonded coatings are also preferred by many engineers and owners as offering better and more rugged corrosion protection than the polyethylene wrapping, which can be easily damaged during and after construction. Historically, procuring a factory-applied lining has been difficult, as domestic US manufactures were united in their positions regarding corrosion protection. 36 More recently, several manufacturers have chosen to offer alternatives that include various forms of bonded coatings or sacrificial coatings, and the need for ductile iron coating standards has now been recognized. The installation of sacrificial anodes whenever a corrosion-related repair is undertaken is standard practice at many utilities. Because the pipe segments are often electrically discontinuous, these anodes may only protect a small portion of main, but evidence indicates that they provide cost-effective life extension to the pipe (see Chapter 5). Steel Aging and Corrosion Protection Steel pipe is different from cast or ductile iron in two important ways: (1) steel pipe has traditionally been designed to more precise thicknesses (without a significant corrosion allowance) and (2) corrosion of steel does not leave behind a graphite residue. These differences have meant that steel has historically been viewed as more vulnerable to corrosion, and therefore was often better protected from corrosion than cast iron when first installed. Current state-of-the-art corrosion protection for steel pipe water pipe includes: Cement-mortar lining, as discussed later Cement-mortar coating or dielectric coating (sometimes both) Cathodic-protection (where warranted by pipe-to-soil potentials) Stray Current Corrosion When direct current passes through the ground, it follows the path of least resistance, jumping on and off metallic pipes that roughly parallel the path of the current. Stray current 35 When the corrodants within the polyethylene encasement are electrically insulated from the anodes within the soil, the cathodic protection is not effective. This is referred to as shielding. 36 Like Henry Ford s Model T, the product came in any color, so long as it s black.

Chapter 3 Material Performance and Corrosion Protection 59 corrosion (electrolysis) occurs where the electric current leaves a pipeline over a relatively small area. Pipelines that are electrically continuous are more likely to attract stray currents and are thus more susceptible. Sources of stray current affecting water mains are the impressed current systems of neighboring utilities, commuter trains and other public transit powered by direct current, and DC power transmission lines. If any of these items are near important metallic pipes, an experienced corrosion engineer should be engaged to assess the potential for electrolysis and design appropriate mitigation measures. PVC Aging In theory, PVC pipes, like other plastics, will slowly stretch over many years, until they eventually burst (like a balloon). In practice, stress levels are such that this does not occur for an exceedingly long time. Much more commonly, small defects in the material lead to small internal cracks that grow slowly until a fracture occurs. These small defects can be simple air bubbles, particles of foreign material, or gouges in the material. How quickly these small cracks grow depends on temperature, the size and spacing of the defects, the properties of the material, the stress levels, and whether there is cyclic stressing of the pipe. Once the fracturing starts, a different phenomenon can sometimes occur rapid crack propagation. A typical PVC pipe crack is on the order of a few feet, but if there s enough energy stored in the system, the crack can extend from one end of a pipe section to the other. Figure 3.5 shows an example where small occlusions in poorly made material led to premature failure of the pipe. The resulting failure split 20 feet of pipe (from bell to spigot). Where the joints of PVC pipe have been fused, cracks extending hundreds of feet have sometimes occurred. Figure 3.5. PVC failure mechanism. Age related failures of PVC pipes are generally attributed to slow crack growth. The crack resistance properties of oriented PVC pipe (PVCO, AWWA C909) is a subject that needs further exploration. PVCO is produced by pulling a newly extruded PVC pipe over a mandrel, expanding it and stretching its length, resulting in a biaxially-oriented molecular structure. The result is a material with greater strength and toughness, which should mean a longer-lasting pipe. However, the higher strength has also meant that thinner pipes are typically used, which may offset the crack-resistance benefits of this product.

60 Answers to Challenging Infrastructure Management Questions UV Degradation, Scratches and Gouges While it is certain that ultraviolet (UV) light from the sun degrades plastic pipe materials, it is less certain whether such degradation has been a significant contributor to premature failures of PVC mains. UV degradation has been detected in pipes that have failed, but the UV damage has been shallow and not directly linked to failures. It is generally recommended that PVC pipe be handled and stored such that UV exposure, scratches, and gouges are minimized, since such damage can ultimately produce failures, although it may take decades for this to occur. The national PVC trade organization recommends exposure to UV be limited to less than 2 years, but with good inventory management, exposure can be reduced to a much shorter period, with little added cost. Pipes that will not be installed immediately should be marked with the date of manufacture when received. Chemical Leaching PVC is fabricated from vinyl chloride monomer (VC), which is a known human carcinogen. VC levels in drinking water are regulated by the USEPA. Additionally, PVC pipe also contains stabilizers, usually organotin (OT) compounds 37 in the United States, which are not regulated but are on the USEPA s Candidate Contaminant List. Using new, more sensitive methods, Project 2991, Vinyl Chloride and Organotin Stabilizers in Water Contacting PVC Pipes (Richardson and Edwards, 2009) found that VC and OT leach from PVC pipe at levels that are near the detection limit of traditional analytical methods. While levels measured in this study never reached maximum contaminant levels (MCL), the Maximum Contaminant Level Goal (MCLG) for VC (0 mg/l) was exceeded. Exposure time (age) and higher temperatures seemed to increase leaching of VC and OT. This study reinforces that minimizing water age and system dead-ends should be criteria applied in the design and operation of distribution systems. Polyethylene Aging In general, HDPE material is very resistant to slow crack growth and is thus a more ductile material than PVC. Historically, cracking failures of HDPE pipes have been rare. A Water Research Foundation study concluded that natural failures of polyethylene pipes are nearly non-existent (Davis, et al., 2007), based on 40 years of use in water systems; the vast majority of failures were attributed to poor workmanship (welds with incomplete fusion) or third-party damage. Current formulations of HDPE are resistant to rapid crack propagation, which is one reason for its broad acceptance for natural gas distribution. Compared to PVC, HDPE has a higher chemical diffusion rate, allowing for faster penetration of oxidants such as chlorine-based water disinfectants. 38 While the amount of degradation that occurs is generally quite shallow, the degraded surface can be a source of microcracks, which can ultimately propagate through the pipe wall. How fast degradation occurs is a function of water chemistry, and other factors. A study by Jana Laboratories (Chung, Conrad, and Oliphant, 2010) reports that chemical degradation rates correlate well with the 37 Organotins are compounds with tin linked to hydrocarbons. 38 This higher diffusion potential also makes HDPE more susceptible to permeation by gasoline and similar hydrocarbons.

Chapter 3 Material Performance and Corrosion Protection 61 water s oxidation-reduction potential (ORP). In potable water, high ORP occurs where ph is low and chlorine residual concentration is high. An earlier study by Carollo Engineers (2008) attributed premature failures of HDPE more specifically to use of chlorine dioxide as a secondary disinfectant (rarely used in the US, but common in France). Suez Environnement (Rozental, 2009) likewise found that oxidation of HDPE occurred 7 times more rapidly with chlorine dioxide than with free chlorine, and that chloramine disinfection produced the lowest oxidation degradation rates. In addition to water chemistry, an HDPE pipe s vulnerability to chemical degradation and crack propagation also depends on temperature, pipe wall thickness, and stress levels. Premature failures of HDPE in the US have occurred with service lines in the Las Vegas area where all three of these characteristics were problematic. These service line installations were very shallow and thus experienced high temperatures much of the time, the ORP was reportedly high, and rock impingement or pipeline kinks caused localized high stresses. Moreover, these small diameter lines have proportionally thin pipe walls, making them more susceptible to cracking. The result was multiple failures in less than 30 years of service. HDPE s higher chemical diffusion rate also means that it is more readily penetrated by small-molecule hydrocarbons. For this reason, it should not be used in gasoline-contaminated soils and other hazardous areas. Project 4138, Chemical Permeation/Desorption in New and Chlorine Aged Polyethylene Pipe (Dietrich, et al., 2010) found that chlorine-related aging of HDPE increases the permeation rate. Hydrocarbon Permeation All plastic pipe, but polyethylene in particular, is rapidly permeated by small-chain, liquid hydrocarbons, most notably gasoline. Instances are relatively infrequent and usually involve gross soil contamination from tanker spills or storage tank leaks. Problems have been more frequent with water service lines than with water mains, probably because of their closer proximity to the contamination and their thinner walls. Gasoline has been involved in the vast majority of cases, but problems have also been recorded with diesel, solvents, and other petroleum distillates, and with naturally occurring petroleum deposits. When hydrocarbon permeation occurs, taste and odor complaints are generally the first sign of a problem, and the water should not be considered safe to drink. Eventually, permeation can also weaken the material, eventually failing the pipe. Hydrocarbon permeation of pipe gasket materials also can occur, and research has shown that gaskets are generally more permeable than the pipe itself. Gasket permeation is not limited to plastic pipe, but can occur wherever certain types of rubber gaskets are used, and many of the materials currently used for pipe gaskets are vulnerable. The fact that documented permeation problems are rare with ductile iron, concrete, asbestos cement, and other non-plastic pipes 39 seems to indicate that the small exposure area offered by a gasket has not been sufficient for detectable permeation to occur. Thompson and Jenkins (1987) concluded that plastic pipe should either not be used or the system should be carefully engineered, and only gaskets that have been shown to be impermeable to the contaminant should be considered, if hydrocarbon contamination of the soil is present or likely to occur. Caution is advised in areas near storage ponds, or land disposal sites 39 Thompson and Jenkins (1987) found three instances of permeation of PVC mains, one instance with CI/Steel, one instance with AC, and no instances with concrete.

62 Answers to Challenging Infrastructure Management Questions for waste water or industrial process water, solid waste disposal sites, or near petroleum or petroleum distillate tanks, pipelines or process facilities. Asbestos Cement Pipe Aging Asbestos cement (AC) pipe was widely used in water distribution mains for decades, but is not installed any more in the United States due to health issues related to fiber inhalation. The performance of the pipe has been fair, with a failure rate that is generally better than cast iron. Invented around 1910, AC pipe accounted for one-third of all water mains being installed by 1960 and constituted 14 percent of the US water main inventory when its use was discontinued about 1980 (Logsdon and Millette 1981). The inhalation of asbestos fibers causes asbestosis (a disease similar to emphysema), lung cancer, and mesothelioma (a cancer of the lining of the lungs), all very serious, potentially fatal diseases. No amount of exposure is considered safe, since a single fiber can lead to cancer; however, asbestos is a natural substance that is found in ambient air all over the world and at certain levels, the health risks are considered small. Concerns regarding asbestos inhalation have led to strict regulation of the work practices and disposal of such materials, and have raised significantly the cost of using and maintaining AC pipe. The ingestion of fibers released into water, although perhaps controversial, has not received the same kind of attention. Ingestion has not been positively linked to health problems, and at present there s no health or regulatory reason to replace existing AC pipe. There is a limit on the number of fibers permitted in drinking water, 40 but testing for asbestos is not generally required. Utilities should be aware of conditions that may cause fibers to be released to the water and perform tests if warranted, since fibers in domestic water could certainly lead to fibers in the air by a number of different mechanisms. 41 Although the performance of AC pipe has been better than cast iron, some utilities are concerned that AC pipe failures may rapidly escalate. Much of this pipe was installed in the 1950s and 1960s, during a time when suburbia was rapidly expanding. Now, with thousands of miles of this 50 and 60-year-old pipe in the ground, examinations often show considerable loss of calcium in many of these pipes. Linear projections of this deterioration have indicated that within a few years, many pipes could have insufficient strength to contain normal operating pressures. AC pipe also has characteristics which make it particularly risky as it ages: The material is brittle and tolerates little strain. This makes it particularly vulnerable to bending failures from ground movement. Calcium Leaching Failures tend to be circumferential, resulting in larger-than-average consequences Special regulatory requirements complicate and add to the cost of AC pipe repair and renewal As AC pipe ages, calcium leaches from the material, particularly where the water is soft, has low ph, or has other aggressive characteristics. The loss of calcium can occur both from 40 The limit in the US (1991) is 7 million fibers, 10 m or longer, per liter of water. 41 Concerns have been expressed about humidifiers and vaporizers, but anywhere that water evaporation occurs a kitchen floor, a clothes dryer, a shower would become a source of air-borne fibers.

Chapter 3 Material Performance and Corrosion Protection 63 the inside and the outside of the pipe, slowly reducing its strength and increasing the risk of a pipe break. Free lime (Ca(OH) 2 ) is the calcium product that leaches most readily. Carbon dioxide in the pore water reacts with the free lime to form CaCO 3, and if sufficient alkalinity exists, this will precipitate and block the pores, slowing or stopping the degradation. However, if the bulk water is undersaturated, the CaCO 3 will also dissolve, leading to continued calcium leaching, including the loss of the more stable calcium silicates. Source: Levelton Consultants, Ltd., Richmond, British Columbia Figure 3.6. Phenolphthalein stain tests and SEM/EDS results for degraded AC pipe. The phenolphthalein stain test (left)indicates free lime is largely depleted (the pink band in the middle indicates undeteriorated material), but the more precise scanning electron microscope/energy-dispersive spectroscopy (SEM/EDS) shows much less calcium loss, particularly on the external side. This illustrates the difficulties in interpreting phenolphthalein stain testing results The phenolphthalein stain test is used in most evaluations of AC pipe, because it is easily performed and shows quite graphically the presence of free lime. Figure 3.6 shows an example of test results for degraded AC pipe. In this example, more than half the pipe wall shows degradation, but the relationship between free lime depletion and actual calcium loss is not very strong, particularly on the external side of the pipe. There have been similar difficulties correlating the loss of free lime and loss of strengths. Many pipes show considerable lime depletion yet still meet the strength tests required for new pipe. Dozens of tests, for instance, performed for the East Bay Municipal Water District (EBMUD) found that nearly all met the strength requirements of new pipe, even though lime depletion was significant (Project 4480, ongoing). Figure 3.7, taken from another utility s study, illustrates that as free lime is lost, strength diminishes, but the data exhibit considerable scatter and the coefficients of variation (R 2 ) are not strong. 42,43 42 While Project 4093 (Hu, et al., 2012) found seemingly strong relationships between degradation depths, as determined by phenolphthalein testing and AC pipe residual strength, the Y-axis variable was calculated using the X-axis variable, creating an autocorrelation, which accounts for most of the correlation..

64 Answers to Challenging Infrastructure Management Questions 14,000 Lab Samples 12,000 Crushing Strength (psi) 10,000 8,000 6,000 4,000 y = -6,679x + 9,828 R² = 0.14 y = -6,103x + 10,848 R² = 0.29 y = -12,255x + 11,296 R² = 0.32 2,000 Source: Alameda County Water District 0 Inner Outer Total 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 Phenolphthalein Unstained Thickness (in.) Figure 3.7. Relationship between AC pipe degradation and strength The leaching of free lime has been the primary focus of most AC pipe assessment tests because it is a well understood, easily measured process. Where free lime is present, it is safe to conclude that very little degradation has occurred, but where free lime is absent, it is much less certain how much strength has truly been lost. The differences between Type I and Type II AC pipe may partly explain why the correlation between free lime depletion and the loss of strength has not been very strong. Type I pipe, the earlier product, contained 15.5 percent free lime; but around 1940, manufacturers in the US and Canada largely transitioned to Type II, a generally superior product. 44 Per ANSI/AWWA Standard C400, Type II pipe could contain no more than 1 percent free lime, so it was considerably less susceptible to calcium loss. 45 The long-term performance of Type II is thus expected to be much better than Type I, and data from the EBMUD study indeed indicates that AC pipe installed before World War II has a much higher failure rate. 43 This scatter is likely attributable to (1) variations in the strengths of the original pipes, (2) the inherent imprecision of the phenolphthalein test method, and (3) highly variable strengths of the deteriorated AC material, due to differences in matrix composition, fiber content, fiber size, and fiber orientation. It can be inferred from Figure 3.7 that interior degradation is more significant and has a stronger influence on strength than external degradation. 44 Type II AC pipe was cured with steam at high pressure. During this curing process, most of the free lime combines with silica powder to form more stable cementitious products. The leaching of the small amount of remaining free lime would thus not necessarily reflect a loss of significant strength. Only if the loss of free lime is also indicative of more substantial calcium loss would the depletion depth be an important strength parameter. 45 After the introduction of Type II pipe, it became the recommended AC product for systems where water was classified as moderately aggressive. ANSI/AWWA Standard C401 provided recommendations for the selection of AC pipe materials based on water chemistry and soil conditions. Moderately aggressive water was defined as water with a negative Langlier Index (i.e., undersaturated for calcium carbonate).

Chapter 3 Material Performance and Corrosion Protection 65 To slow the internal degradation of AC pipe, water conditioning may be effective, including increasing the ph or the addition of alkalinity. Zinc orthophosphate has also been shown to be effective in stopping or slowing internal corrosion. Sulfate Attack or Other Salt Cracking Reactions between sulfate ions and certain calcium products will produce expansive ettringite, leading to cracking of the concrete material. Sulfate is suspected to be a significant factor in AC pipe failures Las Vegas, but the crystallization of other expansive salts may also be involved. Sulfate attack can be confirmed through petrographic analysis and only involves concrete products with tricalcium aluminate in the Portland cement. Per AWWA Standard C401, Type I pipe was considered susceptible to sulfate attack, but Type II pipe was not, but this was probably an over simplification. AC Pipe - Life Expectancy Benchmarking It is common to estimate remaining service lives of pipes and other assets using published figures from AWWA or figures taken from formal and informal surveys of other utilities. In the case of AC pipe, life expectancies are not well established. The majority of such pipes in the United States were installed in the 1950s and 1960s and large scale replacement programs for these pipes have generally not yet been implemented, as failure rates have been moderate compared to cast iron pipes. A problem with life-expectancy benchmarking, as noted earlier, is that the death of a pipe is not a definitive event. The life expectancy of a pipe can be a matter of opinion the pipe dies when someone decides to replace rather than repair it. AC pipe could be something of an exception to this rule. In theory at least, widespread internal degradation could eventually become severe enough that pipes could not be repaired they would be incapable of sustaining internal pressure. Fortunately, to date, there is little statistical evidence that this is occurring. The majority of failures in most systems have been attributed to pipe bending, which is both localized and repairable. Concrete Pipe Aging To a certain extent, the term concrete pipe is a misnomer. With the exception of AC pipe, the strength of concrete pressure pipe is due largely to steel within the pipe, so the focus needs to be on protecting this steel from corrosion. In discussing concrete pressure pipe, it is important to distinguish between non-prestressed and prestressed pipe. Steel Cylinder Reinforced Concrete Pipe (Non-Prestressed) The long-term performance of non-prestressed steel cylinder reinforced concrete pipe (SCRCP) manufactured to ANSI/AWWA Standard C300 has been quite good. Unlike prestressed pipe concrete cylinder pipe (PCCP), which relies on thin, high-strength wires, the reinforcement of SCRCP is larger in diameter, more ductile (grade 40, low carbon), and much less vulnerable to corrosion loss or embrittlement. The steel cylinders in SCRCP are also thicker

66 Answers to Challenging Infrastructure Management Questions than is typically found in PCCP, providing a considerable portion of the pipe strength. The thicker cylinder provides greater corrosion tolerance and more overall ductility. Interior corrosion protection is provided by concrete lining, typically one-inch thick. The performance of concrete and cement mortar linings has been remarkably good in general. While the high-ph provided by cement-based linings eventually disappears as lime leaches from these linings (as discussed later in this chapter), corrosion beneath the linings is limited by the amount of oxygen that is available. While some rusting of the interior surface of the metal does occur, only a thin corrosion layer generally develops. If the corrosion were more extensive, spalling of the lining would be seen (due to expansion of the rust), but this is rare. Exterior corrosion protection is also provided by the concrete. Several inches of concrete generally cover the steel cylinder and one inch of concrete (plus or minus 0.25 inches) covers the reinforcing steel. While this type of pipe has demonstrated good performance, no system of corrosion protection is perfect. Potential flaws in this corrosion protection system are: (1) cracks in the lining and mortar; (2) misplaced reinforcing steel (insufficient cover), and (3) use of calcium chloride admixture to accelerate the setting of the concrete or the joint mortar. Even without these defects, aging of the concrete from various processes eventually negates much of its corrosion-protection properties, but this normally takes many decades. In highly corrosive soils, particularly where chlorides or sulfates are present, the life expectancy can be shortened considerably; in these situations, cathodic protection (CP) has been used effectively. Bar-Wrapped Steel Cylinder Concrete Pipe Pipe manufactured to ANSI/AWWA Standard C303 is similar in many respects to steel cylinder reinforced concrete pipe, except that the exterior reinforcement is continuous and wrapped helically around the pipe under tension. Because of this tension, early versions of this standard called this pipe pretensioned, but in contrast to prestressed pipe (ANSI/AWWA C301), the reinforcement of this pipe is low-tensile (40 ksi yield strength), low-carbon steel, and under modest tension (8 to 10 ksi). The performance of this pipe has likewise been relatively good. Mortar linings and coatings for bar-wrapped concrete pipe are thinner than for C300 pipe. The pretensioning of the reinforcement minimizes cracking of the lining and reduces the chance for cracking of the mortar, but again pipelines in highly corrosive environments often need special corrosion protection provisions, such as CP. Non-Cylinder Reinforced Concrete Pipe This type of pipe is also reinforced with low-tensile (40 ksi) steel. It is limited to applications where pressures are 55 psi and lower. With no steel cylinder, the pipe may leak through cracks. By keeping pressures low, such cracking is minimized. Prestressed Concrete Cylinder Pipe Prestressed Concrete Cylinder Pipe (PCCP, ANSI/AWWA C301) has received considerable attention due its history of catastrophic failures. In contrast to the mild steel used in other concrete pipe, the primary steel in this pipe is high-tensile, high-carbon, and small diameter. This makes the steel much more vulnerable to corrosion and embrittlement. The pipe

Chapter 3 Material Performance and Corrosion Protection 67 is also brittle, in that the difference between the yield and ultimate strengths of the reinforcement provides little ability for stress transfer. Because of how the pipe is engineered, failures tend to be catastrophic. Romer, et al (2008) studied the failure rates of PCCP and found that the date and location of manufacture determined to large extent the likelihood of failure (Figure 3.8). Not surprisingly, this bad pipe was manufactured during a period when standards for the design of PCCP pushed the envelope. Mortar linings and coatings became thinner. Allowable tensile strengths were increased and the minimum size of tendons shrank. Figure 3.9 illustrates many of these changes. Since 1984, the standards for this type of pipe have been strengthened considerably and associated failure rates have dropped. 46 Source: Romer et al. 2008 Figure 3.8. Year of manufacturer versus failure rates for PCCP. The likelihood of PCCP failure is strongly related to the year and location of its manufacture. 46 The spike shown in Figure 3.8 for pipe manufactured in 1988 is not believed representative of the pipe manufactured that year. One stick of pipe failed but the owner decided to replace the whole pipeline.

68 Answers to Challenging Infrastructure Management Questions Source: Romer et al. 2008 Figure 3.9. The evolution of standards for PCCP. Liberalized standards account for high failure rates for pipe manufactured in the late 1960s through the 1970s. Gasket Degradation from Chloramine Project #2946, Impact of Hydrocarbons on PE/PVC Pipes and Pipe Gaskets (Reiber 1993) found that chloramines were injurious to some types of gaskets. For elastomers, solutions of chloramines produced greater material swelling, deeper and denser surface cracking, a more rapid loss of elasticity, and greater loss of tensile strength than equivalent concentrations of free chlorine. The difference was conclusive: chloramines are uniquely injurious to elastomers; more so than other forms of chlorine disinfectants. The elastomers most susceptible to attack are those formulated with natural isoprenes (rubber) or synthetic isoprene derivatives. Only the newly engineered, completely synthetic polymers developed specifically for their chemical resistance performed well in the chloramine exposures. WHAT FACTORS DRIVE OR SLOW METAL CORROSION? As discussed in Appendix A, four elements must be present in order for galvanic corrosion to occur: an anode, a cathode, an electrolyte, and a current path. Electrochemical corrosion is similar. By changing the characteristics of these elements, the rate of corrosion can be accelerated or slowed. Table 3.2 summarizes.

Chapter 3 Material Performance and Corrosion Protection 69 Table 3.2. Factors Which Promote or Retard Corrosion Element Promotes Corrosion Retards Corrosion Anode / Cathode Use of less noble metals (more negative on galvanic scale) Use of more noble metals (less negative on galvanic scale) Use of metals that are far apart on galvanic scale Use of metals with similar galvanic scale values Differing oxygen diffusion at metal Uniform oxygen diffusion and other surface 47 factors High stresses Low stresses Material anomaly Material uniformity Electrolyte Corrosive soil Non-corrosive soil Low ph (acidic) High ph (basic) Aggressive water Benign water Bare metal (direct contact between anode, cathode and electrolyte) Barrier coatings (lack of contact between anode, cathode, and electrolyte) Non-uniform electrolyte Uniform electrolyte Current Path Direct connection between different metals Dielectric (insulating) joints between different metals Bare metal or conductive coating Dielectric (insulating) coatings Factors that contribute to soil corrosivity are summarized in Table 3.3. 47 Crevice corrosion occurs at joints, and surfaces beneath bolts and particulate matter, where oxygen is excluded. Differences in oxygen diffusion has also led to corrosion where pipes cross under sidewalks or pavement.

70 Answers to Challenging Infrastructure Management Questions Table 3.3. Factors Which Affect Soil Corrosivity More Corrosive Less Corrosive Soil Type Clays, mucks, bay mud, adobe clay, organic soils, peat, cinders 48 Moisture Content Moist Soil Electrical Resistance Variable soils can create anodes and cathodes Frequent wet-dry cycles Flowing water Tidal areas Low resistivity (high conductivity) Sands, gravels, well-drained loams Uniform soil conditions Dry soils Aerated soils High resistivity (low conductivity) ph Low (<5.0), acidic High, alkaline Redox Potential Low values (negative) High values (positive) Soluble Salts (Chlorides, Sulfides, Sulfates) High concentrations Low concentrations Predicting when and where corrosion failures will occur, based on the above parameters, has proven to be difficult. Lack of soil uniformity may partly explain this. A pipe that is onemile long may pass through many different soil environments. Even if the native soil is uniform, many pipe trenches are filled with imported materials and records of what was used are often nonexistent. A small anomalous condition can create a corroding anode. Variations in soil moisture also factor in. In most locations, soil moisture will vary considerably with the seasons and the weather. Soil moisture can also vary with the condition of the infrastructure itself. A water system with leaky joints and leaking (often abandoned) services will saturate the soils, accelerate corrosion, leading to more leaks and problems. If a pipeline has been designed and constructed for a highly corrosive environment, the number of leak repairs can remain low. This also may explain why soil corrosivity and main repairs don t always correlate. The problem pipes may be those that were poorly engineered, poorly constructed, with minimal protection. WHAT ARE THE LIFE EXPECTANCIES OF DIFFERENT PIPE MATERIALS? As discussed in Chapter 2, the service life of a pipeline is not a definitive event. Unlike a person, a water pipe can be made to last indefinitely, as long as someone is willing to keep fixing 48 Cinders were once widely used for road surfacing.

Chapter 3 Material Performance and Corrosion Protection 71 it. A pipe lasts until a decision is made to replace rather than repair. While these decisions are often based on how often repairs are needed, many other factors also influence the decisions. 49 Comparison of Main Repair Rates Water main repair rates are commonly expressed as breaks/100 miles of pipe/year. Average rates in the US are about 25 breaks/100 miles/year, whereas in Europe, the average has been reported as 80 breaks/100 miles/ year (Damodaran, et al., 2005; Deb, et al., 2002). In this context, a break is any breech of the pipe barrel requiring a repair, and excludes repairs to service laterals and other laterals. 50 The best comparison of failure rates for different water main materials comes from the United Kingdom (UK), where data are gathered in a uniform manner from all utilities. In the UK, main replacement decisions are driven by meeting various customer service goals established by the Water Services Regulation Authority (OFWAT). Goals include the need to minimize outages, avoid water discoloration, and avoid customer complaints. Utilities are penalized monetarily if goals are not met. Privatization of the UK utilities was undertaken in 1989 largely for the purpose of improving infrastructure investment and levels of service (Van den Berg, 1997). The failure rates shown in Table 3.4 may be evidence that by emphasizing customer service goals, the break rates in the UK are now closer to the US average of 25 than to the European average of 80. 51 49 Many pipes are replaced long before they are worn out. Replacement decisions are often driven by hydraulic improvement projects, community redevelopment, street realignment, and other reconstruction projects. Even when reliability is the prime motivator, financial, social, environmental, and political considerations apply. 50 Unfortunately, this definition is far from universal, even within the utility organizations, such as AWWA. 51 Although, it questionable that the UK rates were ever as high as 80/100 miles/year. A drop from 80 to 25 in a scant ten years would be a remarkable achievement.

72 Answers to Challenging Infrastructure Management Questions Table 3.4. Water Main Failure Rates in the UK UK Failures/100 miles/year 1998 1999 2000 2001 Averages Asbestos Cement 26.4 27.5 24.3 25.4 25.9 Ductile Iron 8.0 8.5 7.7 7.7 8.0 Cast Iron 38.1 38.1 30.7 34.9 35.5 Polyethylene (HDPE and MDPE) 5.6 4.7 5.3 5.0 5.1 PVC 15.4 14.6 11.6 11.9 13.4 Steel 8.0 9.8 9.3 9.2 9.1 Unknown 0.2 0.0 0.0 0.2 0.1 Source: MacKellar and Pearson, 2003 HOW DO THE FAILURE RATES OF DIFFERENT PIPE MATERIAL COMPARE IN NORTH AMERICA? Table 3.4 provided a comparison of failure rates for the UK. This comparison is useful, because the regulatory structure in the UK means that the data are gathered and reported in a consistent way across all utilities. However, differences in performance between the UK and North America exist due to differences in material specifications, construction standards, environmental, and other conditions. In the US, reporting is voluntary, and data gathering and reporting standards are less consistent. The results of a survey of 188 Canadian and US utilities are shown in Figure 3.10. Because HDPE has not been used by US water utilities in large quantities, it does not show up in this comparison, except in the other category, which also includes galvanized steel and copper. The numbers in this figure are based on a single 12-month period, and likely under represent large urban areas where failure rates are higher. As noted earlier, other studies have placed the average US failure rates at about twice what is shown in this figure. 52 52 Water Research Foundation Project No. 4307 (forthcoming) found a break rate of 26/100 miles/year, based on a survey of 27 US utilities. The Water Stats survey (Deb et al. 2002) found similar results, based on 337 participating utilities.

Chapter 3 Material Performance and Corrosion Protection 73 Failure rates from survey of 188 North American Utilities Source: Adapted from Folkman 2012 Figure 3.10. Comparison of North American failure rates The conclusion from various sources is that failure rates for cast iron and asbestos cement pipes are higher than for other materials; this is hardly surprising, and is partly attributable to the older ages of these materials, but also reflects inherent material shortcomings that are now better understood. The failure rates of the modern pipe materials, (ductile iron, PVC, and HDPE) will no doubt increase as these materials grow older, but there is evidence that failures of these materials will remain considerably below that of their predecessors, due to differences in their aging processes. To answer questions about how long different materials really last, a national data base is needed. The challenge is to develop common definitions and protocols so that comparable data are collected on a regular basis and can be readily accessed to produce meaningful information. A current WaterRF Project, Collection and Compilation of Water Pipeline Field Performance Data (No. 4442) aims at this. HOW DO FUTURE FAILURE RATES COMPARE? Table 3.4 and Figure 3.10 showed current failure rates in the UK and the US, but if we want pipes that last 100 years or more, the more relevant consideration is future failure rates. As these pipelines age, which ones will fail more frequently? Although predicting the future is always perilous, decades of experience with these materials provide the basis for some observations. Future PVC Failures Figure 3.11 shows the water industry s best guess for the future failure rates of US-made PVC pipe, based on slow-crack growth. Although PVC material of this type has only been around for 30 years, researchers have projected that failure rates for 100-year old PVC will remain relatively modest, less than half what is being experienced for cast-iron and other older pipes.

74 Answers to Challenging Infrastructure Management Questions Using Weibull analysis and Monte Carlo simulation, graphs predicting future failure rates have been generated. This graph is for US made 8-inch PVC. Note that these failure rates are per 100 km not 100 miles. Source: Burn et al. 2005 Figure 3.11. Predicted PVC failure rates In addition to the relatively low failure rates, there are two other things worth noting in this graph: Future failure rates can be dramatically lowered, if the pipeline is conservatively designed. If the stress level is lowered by only 6 percent, the 100-year failure rate drops by 60 percent. Lowering the stress by 17 percent reduces failures by 85 percent! Failures increase, but at a decelerating rate. This implies that failure rates with PVC will typically remain manageable. In fact, if stresses are low enough, the failure rate will almost level off, as shown in the lowest curve. Future HDPE Failures Figure 3.12 shows a similar graph for slow-crack growth failures in HDPE pipe. Compared to PVC, the rates are much lower. However, this graph is likely overly optimistic. Chemical degradation from exposure to chlorine was not considered in generating this graph. Testing by Jana Laboratories Report indicates that more than 100 years of service life can be expected for the majority of HDPE water mains in the US. These estimations are based on accelerated aging tests of small-diameter (thin-walled) service lines, performed in accordance with ASTM F2263, Standard Test Method for Evaluation of the Oxidative Resistance of Polyethylene (PE) Pipe to Chlorinated Water. For thicker-walled water mains buried at greater depth, significantly longer lives would be expected.

Chapter 3 Material Performance and Corrosion Protection 75 This graph was developed in the same way as the earlier PVC graph, using Weibull analysis and Monte Carlo simulations. Note the Y-axis scale is logarithmic and the values are extremely low. The low future failure rates shown here are likely overly optimistic because chemical degradation has not been considered in the analysis. Source: Davis et al. 2007 Figure 3.12. Predicted HDPE failure rates. Future Ductile Iron Failures Unfortunately, we don t have similar graphs that predict future failures for ductile iron pipe, but we know from experience, that failures of such pipelines can sometimes increase exponentially that is, at an accelerating rate. But we also know that sometimes the rates hold rather steady, as shown in Figure 3.13. Source: Rajani et al. 2011 Figure 3.13. Examples of increasing and steady rates of ductile iron failure. Exponential increases would be expected where the pipe is relatively thin and buried in relatively hot soils, without corrosion protection. More steady failure rates would be expected for the opposite conditions (thick pipe in less corrosive soils). This is the same pattern that we ve seen for many decades with cast iron pipe. We have also seen cases where the failure

76 Answers to Challenging Infrastructure Management Questions rates start to increase exponentially, but then level off, once the pipes in the hot-soil areas are replaced. When polyethylene sheet wrapping is used effectively, the pipe should behave more like a thick pipe in relatively non-corrosive soils with relatively rare failures and without a steep acceleration in rates. However, there are cases where ductile iron, even with a good protective wrapper may not be a good choice. In areas where the groundwater is shallow and fluctuates, for instance, special protection of ductile iron may be needed, or the use of a different pipe material. WHY IS PORTLAND CEMENT SO EFFECTIVE IN CORROSION PROTECTION OF PIPES? Cement mortar lining s protection of the underlying metal is due to three synergistic properties: (1) it acts as a barrier to elelctrolyte; (2) its high alkalinity passivates the metal; and (3) its reacts chemically with the infiltrating water further inhibiting corrosion. The combination of these three properties makes cement mortar lining quite effective. It s also inexpensive and durable. As a barrier to electrolyte, cement mortar is inferior to most other coatings, particularly when first placed in service. However, unlike most barriers, its effectiveness often increases with age. The electrical resistivity of cement mortar is initially low, and increases as the mortar continues to cure over time. Cement mortar also has the ability to self repair. Small cracks and voids are closed either by the expansion of the mortar when it is immersed, or by the leaching and deposition of calcium carbonate and calcium hydroxide crystals under certain circumstances. As the lining permeability decreases, the effectiveness of the barrier coat increases. The alkalinity of Portland cement is very beneficial in preventing corrosion of ferrous metals. With a ph of 12.6 or greater, Portland cement mortar or concrete creates a zone of passivity at the metal surface that does not facilitate corrosion. This passive zone can also extend across small imperfections in the lining, as long as alkalinity remains high (i.e., there is little movement of water through the crack). Passivation generally exists where the ph is above 10.5. The passivation property of Portland cement can be compromised if chloride ions are present at a concentration of 700 ppm or greater along with atmospheric oxygen. Passivation can also be negated due to stray current electrolysis or overactive cathodic protection. The third corrosion-inhibiting quality of cement mortar and concrete is that it tends to alter the chemistry of infiltrating corrodants, or react with the corrodants and physically block the intrusion of more. HOW LONG WILL THE CEMENT MORTAR LINING LAST? Cement mortar lining (CML) has been proven to be an extremely effective corrosion control method, but like everything, it deteriorates over time. In soft water, calcium leaches out. This reduces the alkalinity to the point that the ph protection is gone in about 35 years (Muster, et al., 2011). To counteract this, a seal coat is often applied to factory-produced linings. Linings that are applied in place are less dense, don t have a seal coat, and have a significantly shorter high-ph life. The loss of the calcium also weakens the mortar. In large-diameter pipes, the weakening can sometimes lead to a collapse of the lining. In hard waters, the ph protection also goes away due to chloride penetration. (Chloride negates the ph protection, resulting in

Chapter 3 Material Performance and Corrosion Protection 77 corrosion.) Although chlorides are not present in high concentrations in potable water, they tend to be higher in harder water. Does this mean that the CML corrosion protection stops working after 35 years? The evidence says no. Corrosion will often be found under the lining, but not a lot of corrosion. If corrosion were substantial, the expansive rust would pop off the lining, which does not happen often. This may be because the lining is still a fairly good barrier, passivating the pipe surface by stopping oxygen transport. The oxygen barrier may be particularly effective in hard water, where autogeneous healing occurs if high levels of magnesium or silicon exist (Parks, et al., 2008). HOW WELL DO THE DIFFERENT PIPE MATERIALS PERFORM IN EARTHQUAKES? By studying the performance of different types of water mains following major seismic events in Japan, the US, and elsewhere, Ballantyne (1994) and Eidinger and Davis (2012) have determined that pipelines which do well in earthquakes have the following characteristics: Joints that do not easily pull apart Joints that do not easily fail from axial movement or angular rotation Pipes made with ductile material Strong, undegraded material Table 3.5 provides a general guideline for expected seismic performance, based on pipe characteristics and the failure rates observed in various earthquakes:

78 Answers to Challenging Infrastructure Management Questions Table 3.5 General Comparison of Seismic Performance of Common Water Main Materials Pipe Material Seismic Vulnerability Factors Affecting Seismic Performance Cast Iron Asbestos Cement Highest seismic failure rates of all common water main materials Second highest seismic failure rates Rubber gasketed joints perform better than leadfilled or leadite -filled joints Corroded pipes perform worse than noncorroded material Brittle material can withstand very little strain Brittle material can withstand very little strain Ductile iron Steel Excellent performance with restrained joints 53 Relatively poor performance with unrestrained joints Good performance with welded joints Ductility and strength allows for considerable ground movement, if joints are restrained Short joint insertion lengths mean that pipe readily pulls apart if joints are not restrained Ductility and strength allows for considerable movement, if joints are restrained PVC Moderate vulnerability Long joint length allows for some extension before failure occurs Axial compression can cause over-stabbed joints and eventual failures HDPE Very good performance Good ductility and fully-fused joints allow for considerable movement without failure Sources: Ballantyne 1994, Eidinger and Davis 2012 CAN I MAKE THE NEW PIPES LAST LONGER? The longevity of new pipes can generally be increased, simply by using more conservative design criteria. Many of today s failures are attributable to economizing on materials, omitting corrosion protection, and allowing higher stresses than a long-term view would dictate. Paying a little more at the beginning for the appropriate materials, good coatings, good bedding, full-time inspectors, a little extra wall thickness, and cathodic protection adds little to project costs, but extends by many decades the life expectancy of the pipes. When constructing a new pipeline in an existing urban, the cost of the pipe material and its corrosion protection are very, very minor factors. The major costs involve digging, backfilling, and paving the trench. Yet we often scrimp on the most important parts of pipeline design. In a study by the Los Angeles Department of Water and Power, the cost of the pipe 53 In Japan, a special type of ductile iron pipe joints locks firmly yet allows axial extension/compressions and joint rotation. No seismic failures of this type of pipe have occurred even though it was severely tested in the Great East Japan (Tohoku) Earthquake of March 2011

Chapter 3 Material Performance and Corrosion Protection 79 material was estimated at only 5 percent of the cost of the project (Ellison, et al., 2012). Yet, we often select the least expensive, thinnest, weakest and least protected materials that current standards allow. For plastic pipes (PVC in particular), significant life extension is possible by reducing stress levels and minimizing cyclic loadings. As noted earlier, Project 2879 (Burn, et al., 2005) showed that by reducing stress levels by 6 percent, 60 percent fewer future failures would accrue, and by reducing stress levels by 17 percent, 85 percent fewer failures would result. In other words, installing a Class 200 pipe where the operating pressure is 150 psi or less, could produce large future dividends. Yet, changes in the PVC pipe standards have gone in the opposite direction, reducing the initial safety factor for PVC pipe, and thereby increasing the average stress level. The result will be higher rates of future failures. Likewise, a very recent reduction in the safety factor for HDPE was proposed and was hotly debated but passed. In Project 4034, Failure of Prestressed Concrete Cylinder Pipe, Romer, et al., (2008) presented a similar story. The research team found that many (if not most) of the problems associated with prestressed concrete cylinder pipe were attributable to a steady weakening of the standards, allowing thinner cylinders and more highly-stressed tensioning, neglecting the fact that such changes inevitably shorten the life expectancy of the pipe by making materials more vulnerable to the deterioration that is always sure to occur. For many years, standards have allowed the installation of unprotected iron pipe, under the assumption that this was acceptable for certain soils, but as Romer and Bell (2005) pointed out, the result has been continued corrosion and deferral of expenses to future generations for the sake of minor cost savings in the present. They advocated a change to a risk-based approach involving four simple steps: assessment, evaluation, implementation, and monitoring, along with a commitment from management. CAN I MAKE THE EXISTING PIPES LAST LONGER? Although our ability to change something buried below a busy street has limits, successful strategies have been implemented that reduce failures and prolong the life expectancies of mains: Lining Programs Cleaning and lining of unlined cast-iron and steel pipes using cement mortar or polymer stops internal corrosion and also plugs small holes. As discussed in Chapter 6, sharp reductions in leakage rates have been documented. The Los Angeles Department of Water and Power credits a large-scale cleaning and lining program for much of the decline in failure rates that it has experienced over the last 10 years (Figure 2.7). CP System Retrofits Installation of cathodic protection systems on existing water pipes has been successful for dozens of utilities. The best candidates are electrically continuous transmission pipelines with few lateral connections and good exterior coating systems, but less-than-ideal pipelines have been protected as well, using both sacrificial and impressed-current systems. For pipelines that are electrically discontinuous, Romer and Bell (2005) suggest installing sacrificial anodes at every other pipe joint. This reduces by 50 percent the number of excavations that a joint-

80 Answers to Challenging Infrastructure Management Questions bonding effort requires. Anode installation has been successfully demonstrated using vacuum excavation and keyhole methods. 54 Pressure Management Pressure reduction and surge protection will reduce leakage volumes and break rates. Bargmeyer, et al., (2004) demonstrated that surge events are a fairly common occurrences on many systems, and a report for the City of Los Angeles (Bardet, et al.,2010) attributed a sharp increase in cast-iron break rates to pressure spikes related to a water rationing schedule. With brittle pipe materials, even moderate pressure fluctuations may produce material damage and eventually trigger breaks. Some utilities have reported success in reducing leakage and breaks using pressure-reducing valves that are programmed to reduce system pressures at night, when demands are low. Water Conditioning The rate of internal corrosion of AC pipe and cement mortar linings, as well as copper and lead components, can be reduced by changes in water chemistry, as discussed in Chapter 4. The life expectancies of some assets may be increased by many decades. Break Repair Anodes Many utilities routinely install sacrificial anodes during break repairs. The anode protects the pipes to which it is attached and often several surrounding pipes where incidental conductivity exists. A study of the City of Hamilton, Ontario, showed that the cost of the anodes was repaid by the savings in avoided future repairs (Gustafson, et al., 2007). The avoidance of break-related community impacts add to these benefits. HOW DO THE FAILURE CONSEQUENCES OF DIFFERENT MATERIALS COMPARE? Chapter 2 discusses the concept that risk has two dimensions: the likelihood of failure and the consequences of failure. Most of the discussion in the current chapter has been on material aging processes and how these affect the likelihood and frequency of failures. However, all failures are not equal. A leak that releases several gallons a minute is quite different from a fracture that gushes thousands of gallons per minute. Water main failures span the continuum between small, manageable failures (i.e., a leak) and large, catastrophic ruptures (i.e., a blow out). Studies of repair costs show the cost of failures can vary significantly. Gaewski and Blaha (2007) studied 30 large diameter breaks and found the cost varied from $6,000 to $8.5 million with a median cost of $0.5 million. Their study showed that the indirect costs (societal, environmental, and property damage paid by others) were often higher than the costs directly paid by the utility. The cost of failure appeared most influenced by (1) the time required to contain the break and (2) where the break occurred. 54 Keyhole methods as described in Chapter 6, were used in the City of Des Moines to install sacrificial anodes at a cost of roughly $10 per foot of main. The City estimated that a 20-year life extension could be achieved at less than 10 percent of the cost of main replacement (Klopfer and Schramuk, 2005).

Chapter 3 Material Performance and Corrosion Protection 81 Pipe diameter was not a strong influencer on cost, but the data set was small. Cost was very much affected by the location of break, with breaks in dense urban areas being more costly. Although the difference in cost between a leak and a blow out is considerable, most data sets in the water industry treat both failures equally. Both are counted as breaks in most industry reports. LADWP, however, does distinguish between a leak and blow out. By LADWP s definition, a blow out is a failure that causes more than 100 square feet of pavement damage. A study for the LADWP (Ellison, Bell and Ballantyne, 2012) concluded that on average a blowout cost the utility three times as much as a leak. 55 Additionally, there are other risks associated with pipeline failures that are difficult to monetize, but need to be considered. These include risks to public health, loss of confidence in the utility, and damage to a utility s reputation. These risks increase with the frequency of failures and the size of the failure. Considering all these factors, Friedman, et al. (2010) recommended a break rate goal of no more than 15 per 100 miles per year, as a way of optimizing distribution system performance. Crack Propagation The failure of a brittle pipe will be more costly than the failure of a ductile pipe. Ductile iron replaced cast iron because it was far less prone to cracking. Ductile iron failures tend to be relatively manageable. Likewise with steel; seldom does it fail catastrophically. When catastrophic failures occur with ductile iron or steel water mains, they generally result from an unusual circumstance where the pipe corrosion is more general (rather than pitting), or where a bad weld or other major structural flaw exists. Partial penetration longitudinal welds have been the source of long-running cracks in several failures. When PVC fails, on the other hand, the failure is nearly always brittle. Typical cracks are on the order of several feet, but if there is enough energy stored in the system, the crack can travel at hundreds of feet per second, faster than the energy is relieved (i.e., rapid crack propagation). Cracks extending from one end of a pipe section to the other from bell to spigot, or 20 feet are not rare; and when fused PVC 56 has been used, much longer cracks have occurred. For steel water mains, rapid crack propagation has occurred along poorly designed or poorly made welds, but long cracks in mild, low-carbon steel are rare events with water mains. HDPE is very resistant to crack propagation and has been widely adopted in the natural gas industry partly because of this resistance. 57 The failure risks associated with any given pipe will depend on its material, as well as other factors such as diameter and location. Table 2.2 provided a summary of these factors. Table 3.6 presents some of the general risk factors associated with the materials. 55 The LADWP definition of a blowout is a failure resulting in 100 square feet of pavement repair. All other main failures are classified as leaks. 56 Fusible PVC has been promoted as an alternative to HDPE, for slip lining, pipe bursting, and horizontal directional drilling applications. A special, proprietery formulation of PVC is used, and fusion is done in a similar manner as with HDPE, but following different temperature and pressure parameters. 57 In natural gas piping, considerable energy is stored in the compression of the gas, so concerns about RCP are acute.

82 Answers to Challenging Infrastructure Management Questions Table 3.6 General Comparison of Risk Factors for Common Water Main Materials Pipe Material Common Failures Failure Frequency Failure Consequences Cast Iron Rust holes from corrosion pitting Cracks / fractures Highest failure rates of all common water main materials Long-running cracks are possible, but driving energy is generally less than fracture energy Asbestos Cement Cracks / fractures Second highest failure rate of all common water main materials Long-running cracks are unlikely; driving energy is generally less than fracture energy Ductile iron Rust holes from corrosion pitting Cracks (rare) Moderate failure rates when appropriately protected from corrosion Failures tend to be moderate. No instances of rapid crack propagation in ductile iron water mains were found in the literature. Steel Rust holes from corrosion pitting Rupture from bad welds (rare) Rupture from general corrosion (rare) Moderate failure rates when well protected from corrosion High failure rates when poorly protected (e.g., galvanized steel) Failures tend to be moderate. Longrunning cracks arising from bad welds are rare in water pipes. PVC Cracks / fractures Third-party damage Moderate failure rates, particularly when used at low stress levels Cracks are often several feet in length. Susceptible to RCP, particularly in defective material. HDPE Third-party damage Poor quality welding Cracking (rare) Lowest failure rates of common water main materials Very resistant to crack propagation. Failures tend to be moderate, arising from bad welds at joints or third party damage. Concrete Cylinder Pipe (nonprestressed) Leakage at joints caused by bad mortar or workmanship Pipe rupture (rare) Low failure rates Failures tend to be moderate, but are difficult to repair. No instances of RCP in water mains are known. Cylinder leakage (rare) Concrete Cylinder Pipe (prestressed) Pipe rupture due to wire breakage Leakage at joints caused by bad mortar or workmanship Low failure rates, particularly for well-made (e.g., post-1984) pipe Failures tend to be catastrophic and difficult to repair. Failures of PCCP generally result in the highest consequences. IN SUMMARY, WHICH PIPE MATERIAL PERFORMS BEST FOR WATER MAINS? Each of the common modern water pipe materials performs well when used in the right environment, subject to the right loading conditions; conversely, each also has its limitations.

Chapter 3 Material Performance and Corrosion Protection 83 Both history and material science have shown that a conservative approach, investing a little more in materials, design, inspection, and construction (including corrosion protection), can pay dividends in the long-term. Water engineers have traditionally designed pipes by applying a standard safety factor to the calculated hoop strength. This was meaningful 100 years ago, when all water pipes were metallic and our knowledge of pipe failures was limited. Criteria for 21st Century pipe design should also include: Life-cycle analysis of corrosion and other material degradation processes Projections of long-term failure rates, with the idea that failures should not rapidly accelerate Acknowledgement that the size of the failure matters, and resistance to crack growth and propagation is therefore very important, particularly for largediameter pipe WHAT PIPE SHOULD I USE FOR SERVICE LINES? While the failure of service lines is seldom catastrophic, frequent failures are costly. Project 2927, Installation, Condition Assessment and Reliability of Service Lines (Le Gouellec and Cornwell, 2006) determined that soil corrosivity, stray electrical currents, bedding conditions, temperature, and other conditions can degrade buried service lines. Line failures are often caused by improper use of backhoes, tampering, improper installation, poor materials (evidenced by wide-spread failures), and lack of supervision (i.e., inspection of workmanship). Because service lines are thin-walled and often very shallow, they degrade and fail in different ways than mains. Plastic lines, in particular, have experienced premature failures from rock impingements, overstresses at connection points, and early chemical degradation. Early failures of HDPE service lines were found in the Las Vegas area, where high temperatures and water chemistry accelerated the aging processes of the thin-walled pipes. In an early study (Thompson and S.A. Weddle, 1992), 31 utilities were surveyed regarding plastic service pipes. Of those, 14 used PE pipe predominantly, 10 used polybutylene (PB) pipe predominantly, and 7 used both. For PE pipe users, 57 percent reported high-tomoderate failure rates, with 43 percent reporting "none." For PB pipe users, 80 percent reported high-to-moderate failure rates. Overall satisfaction rates of 81 and 41 percent were reported for PE and PB users, respectively. PB service lines are no longer used, but left a notion that poly lines were problematic, to the chagrin of the HDPE suppliers. Copper service lines have traditionally performed quite well, but failures have risen as two changes in the water industry have occurred. First, the adoption of plastic water main materials has removed the unintentional cathodic protection that was once applied to many service lines. The small copper cathode was amply protected when connected to large iron main anode. Although this was detrimental to the main, it certainly increased the life of the lateral. Romer and Bell (2005) recommend the installation of zinc anodes to protect copper service lines, where external corrosion failures have been experienced. Alternatively, the use of HDPE can be considered. The second event leading to increased copper line failures was the substitution of chloramine as the secondary disinfectant in many systems. When chlorine was used, a uniform corrosion layer would form on the inside of copper pipes, which generally protects them from additional corrosion, but in chloraminated systems, this protection has sometimes failed to form.

84 Answers to Challenging Infrastructure Management Questions Without the needed corrosion layer, copper service pipes often fail from corrosion pitting. Fortunately, there is a simple solution; this protection is achievable in chloraminated systems, by curing the lateral with highly chlorinated water, which is often what occurs as the system is initially disinfected, before flushing the pipe and placing it into service. Corrosion of copper laterals is also attributed to use of plumbing for electrical grounding (Duranceau, et al, 1996). Some electronics (variable speed motors, televisions, computers, etc.) produce DC currents on the copper service pipes. Increases in corrosion rates due to DC currents are well documented. Further, when electrical transformers serve multiple buildings and customers, water services and distribution piping can act as parallel neutral return paths for AC from building electrical systems to the transformers. This can increase the rate of corrosion of distribution and service piping, leading to premature failures as well as possible water quality issues. Shock hazards to water utility workers are widespread and well documented. It is recommended that water utilities confer with their local building officials to verify that plumbing systems are not used for primary grounding. HOW LONG DO VALVES, HYDRANTS, AND OTHER SYSTEM APPURTENANCES LAST? The mechanisms and seals in valves, meters, hydrants and other appurtenances generally have a much shorter life expectancy than the pipes, but they are not always replaced or serviced in a timely manner. Often they simply stop working. Old, inoperable equipment is common throughout many water distribution systems: valves that won t close, or with stems that break when used; meters that rotate sluggishly; and hydrants that won t reseal, once they re been opened. When these components don t work, the system cannot be relied upon to perform its functions a particular concern in emergencies. The malfunction of some components pressure reducing valves and vacuum release valves can actually endanger other portions of the system, or lead to property damage. At the least, if these components aren t working, water may be wasted and revenue may be lost. A regular program of functional testing and exercise is needed to assure that most components are maintained in operable condition. For valves, this means assuring that closure is achievable (not just movement of the stem). 58 Exercising of isolation valves and hydrants is sometimes done in conjunction with a unidirectional flushing program, as described in Chapter 4. A consequential benefit of such a program is that many valves and hydrants are regularly tested and exercised. While the crews are at it, they might easily exercise the rest of the valves and hydrants as well. A typical water distribution system has many different kinds of isolation valves each with different characteristics. Some open by turning clockwise; others open counter-clockwise. The number of turns to fully open and close varies. Such information is important to a system operator who is trying to stop a torrent of water in the middle of the night. As part of a regular valve-exercising program, the valve information can be recorded and stored for easy retrieval. Some utilities include the information on valve tags stored under the valve cap, making the data readily available to the operator. Others are now storing the information on their GIS and issuing laptops or tablet computers to the field crews. 58 See WaterRF Report 4188 (Marlow and Beale, 2012) for guidance regarding assessment of valves and other water main appurtenances.

Chapter 3 Material Performance and Corrosion Protection 85 It s important to know whether a valve is supposed to be normally opened or closed, and have some assurance that it s in the right position. Unfortunately, many systems have valves somewhere in the network that are closed and shouldn t be. This creates situations where adequate fire flows are not possible and customer service may be compromised. A valveexercising program hopefully will discover and correct these problems. A valve that gets constant exercise is the pressure-reducing valve (PRV) even the best ones can wear quickly. How long PRVs last depends on the pressure differentials, the flow rates, and the qualities of the water. One leading manufacturer recommends a service cycle of every two years, but some utilities have had success with maintenance cycles of five years and more. Maintenance of PRVs is very important, because their failure can cause over pressurization of the system downstream. To assure that fire flow is always available, most PRVs are designed to fail in the open position, which can damage mains and plumbing systems. Regular scheduled maintenance is therefore important, along with good record keeping. The regular testing and systematic renewal of meters is very important for protecting the utility s revenue. As meters age, they become less efficient, turn more slowly, and record less and less of the water that is consumed. A program of regular testing and renewal can thus pay for its cost many times over, by increasing billing revenue. When consumption is not being accurately recorded, replacement should be scheduled. When implementing a program of pipeline renewal, consider replacing or refurbishing most of these components at the same time. Putting an old valve back into service on an otherwise refurbished system is like installing old spark plugs in a rebuilt engine. The parts may not be fully worn out, but the marginal cost of installing new parts is low. The result is a more reliable system overall, one that is ready for the next fifty or more years of service. HOW LONG WILL TANKS AND RESERVOIRS LAST? The key to long-term performance of most tanks and reservoirs is preventing deterioration through well engineered and applied corrosion protection. Like the Golden Gate Bridge, well-designed water storage facilities can last nearly indefinitely with regular inspection, maintenance, and repairs. Corrosion Protection of Steel Tanks and Steel Roof Structures Before the 1970s, the standard coating system for steel tanks and steel roof structures consisted of lead-based primers and alkyd paints for the exterior and coal-tar enamels and related coal-tar paints for the interiors. While these coatings worked very well, due to health concerns they are no longer applied. Typical modern systems now consist of multiple layers of NSF61- certified epoxy on the interior and one or two epoxy layers topped by polyurethane on the exterior. There are other coating systems that meet AWWA standards, but application problems are more frequent with zinc-rich primers or fast-setting polymers like polyurea. As coating systems age, they eventually become brittle and crack; where exposed to sun light, the coatings also become chalky and porous and weather away. Defects in the material and workmanship also permit corrosion to take root. The quality of the coating design, construction, and inspection are very important, determining to a large extent how well the system will work and how long it will last. Figure 3.14 contrasts the systems inside two steel tanks, showing why experience and expertise in coatings work is important. To assure the long-term economical

86 Answers to Challenging Infrastructure Management Questions performance of any coated tank, frequent inspections, periodic repairs, and occasional recoatings are needed. Figure 3.14. A tale of two tanks illustrates the importance of quality coating work. On the left, a system over ten years old looks almost new. On the right, sheets of paint are peeling after only a few years. Attention to details, good workmanship, good materials, and expert inspection are all needed for quality assurance. Tank coating systems are also often supplemented by cathodic protection systems, which work well in protecting the submerged surfaces from corrosion. Unfortunately, CP systems provide no protection to the steel above the water level, where conditions are often most corrosive. For this reason, CP systems do not necessarily extend the period between coatings, but they can make the recoating work less costly by minimizing the amount of damage that occurs. Either sacrificial or impressed-current CP systems can be used. Where a source of power doesn t exist, sacrificial systems can be designed to be self powering. CP systems have also sometimes been used to protect the underside of steel tanks, but a more common system of protection consists of elevating the base of the tank above surrounding grade and founding it on well-draining aggregate material with a subdrain system to carry water away. Aging Processes for Concrete Tanks and Reservoirs Compared to steel tanks, concrete tanks and reservoirs require less frequent maintenance, but they do deteriorate from several processes, so periodic inspection (interior and exterior) is still needed. The common aging processes and associated protections are described below. Calcium Leaching The earlier discussion on AC pipe described calcium leaching in detail, but for concrete reservoirs and tanks, the concern is less about loss of strength than loss of protection for the reinforcing steel. As calcium is lost, the ph protection afforded by the concrete diminishes, and the concrete becomes more porous, making it easier for water to reach the underlying steel. But because the reinforcing steel is generally well below the surface, many decades of leaching must

Chapter 3 Material Performance and Corrosion Protection 87 precede the start of corrosion, even where water is aggressive. As discussed earlier, if the water is sufficiently alkaline, calcium carbonate will precipitate in the pores, slowing the leaching of calcium by decreasing the porosity. Magnesium and silica in the water may also reduce the porosity. Under ideal conditions (particularly in the absence of chloride), 100 years of service may be a realistic expectation for a well designed and constructed concrete reservoir. Carbonation Carbonation is the reaction between carbon dioxide (CO 2 ) and calcium hydroxide (Ca(OH) 2 ) producing calcium carbonate (CaCO 3 ). The carbon dioxide may be dissolved in water or atmospheric. The carbonation process slowly reduces the ph protection of the reinforcing steel and causes moderate weakening of the concrete. Carbonation is a particular concern in marine and other especially corrosive environments. Alkali-Silica Reaction Alkali-silica reaction (ASR) is a chemical reaction that occurs at the surface of certain types of aggregates (non-crystalline silica), in reaction to the high alkalinity of the concrete. The reaction is hydrophilic and expansive, meaning it pulls in water to form a gel. Expansion of the gel (the dark substance in Figure 3.15) creates pressure that cracks the concrete in a seemingly random pattern. If the concrete is confined or under a compressive load, the expansive forces can be counteracted, and the cracks will appear less random, running perpendicular to the direction of the compression. Cracking will generally first appear near the edges of structures, where there s less confining stress, such as near the tops of walls or the edges of slabs. The random pattern of cracking and the dark staining of the cracks are indicative of ASR. In this case, ASR was one of several reasons that replacement of this tank was needed. ASR has the potential of causing significant damage, but more often the damage remains minimal for many decades. Source: California Water Service Company Figure 3.15. Alkali-silica reaction cracking of a concrete tank ASR has the potential of causing great structural distress. In one instance, ASR cracking necessitated the partial demolition of a large concrete dam 13 years after its completion, reducing the reservoir capacity by 70 percent. 59 For other structures, the ASR cracking may not be noticed until decades after the original construction. Although the degradation usually 59 The Matillija Dam in Southern California.

88 Answers to Challenging Infrastructure Management Questions progresses very slowly, it has been known to rapidly accelerate; the cracks allow water to penetrate, producing more gel, causing more cracks. This is a particular concern for water retaining structures, where the concrete is continuously saturated. There s no way to stop ASR once concrete has been placed and hardened, and it s very difficult to predict the degree of damage that will result. The rate of progression and extent of deterioration vary widely, depending on the characteristics of the concrete mix and the environment. The best assurance against ASR is selection of aggregates with minimal reaction potential, and several laboratory ASTM tests exist, but results can sometimes be ambiguous. Lithium admixtures and the use of fly ash to reduce concrete alkalinity have also been successful. Other Concrete Cracking Virtually all concrete structures have some cracks, but few are considered structurally important. To distinguish important from merely cosmetic cracks, a structural engineer must often be consulted. But even non-structural cracks can be a concern, if leakage results. Knowing the cause of cracking is important for selecting appropriate mitigations or repairs. Structural Cracks. Structural cracks are the greatest concern and occur when the loading exceeds the capacity of the structure. Differential settlement is a common example, but design errors, construction errors, and unexpected loadings can also be causes. Shrinkage Cracks. Shrinkage of the concrete as it dries is the most common source of cracking. In well-designed structures, crack-control joints and construction joints are designed to accommodate most of the shrinkage, minimizing the cracking. Crazing cracks are shrinkage cracks that occur on the surface of quickly drying concrete, particularly where water has been inappropriately added during finishing. These cracks may reduce the durability of the concrete, but generally are not structural concerns. Cold Joints. Partial cold joints result from the poor consolidation between two layers of concrete. While these cracks are generally not structural concerns, leakage from water retaining structures may result. Mitigating Concrete Deterioration Sealers and Coatings Sealers can reduce calcium leaching and carbonation, and may reduce ASR expansion. Silanes and siloxanes are sealers that penetrate into the concrete pores then harden into solid silica-based polymers, blocking the pores. Silicates are densifying sealers that react with calcium hydroxide within the concrete, filling the pores with a crystalline product that hardens the concrete surface. These products can be spray-applied or brushed onto the surface. Epoxy or other polymer coatings are applied to the surface where tank contents or vapors are acidic. If a sealer or coating is needed, the sooner it is applied the better.

Chapter 3 Material Performance and Corrosion Protection 89 Crack Injection and Sealing Epoxy injection seals cracks and can restore a portion of the strength that has been lost, but is only appropriate for cracks where continued movement is not expected. Often, where shrinkage or temperature-related cracking has occurred, injecting epoxy may simply cause another crack to form nearby. For working, non-structural cracks, a better solution may be routing and sealing with an elastomeric caulk such as polyurethane. Membrane liners have also been used to stop leakage through working cracks and from leaky basins and reservoirs. WHAT CAUSES TANKS AND RESERVOIRS TO FAIL? It s difficult to generalize about tank and reservoir failures, because there are so many varieties, but many fail because they no longer meet current standards for health protection and safety, either because they were built to earlier standards or have deteriorated due to neglect. Contents leak out and dirt, debris, and other contaminants leak in. Catastrophic failure of a tank or reservoir is not common, but has occurred, particularly where corrosion is not easily detected, or where the facility was inadequately designed for the loading conditions. Historically, many tanks and reservoirs have failed in earthquakes. HOW WELL DO TANKS AND RESERVOIRS PERFORM IN EARTHQUAKES? For many tanks and reservoirs, seismic resistance was not a design consideration, but the 1971 San Fernando earthquake was a turning point. Since then, tanks in high-seismic regions conforming to AWWA standards must take into account seismic forces. But just as buildings need not be retrofitted every time standards change, utilities are not obligated to address tanks and reservoirs that were constructed to earlier standards. So this begs the question, when should a tank or reservoir be upgraded? When a major earthquake occurs, a utility s tanks and reservoirs will be its most important facilities. Experience has shown that pumping operations will be interrupted due power outages, and water supplies may be disrupted, due to transmission pipeline problems. During this time, the storage in elevated reservoirs becomes the only water for fire fighting and sanitation. Their importance requires tanks and reservoirs be designed, constructed, and maintained to the highest standards. Yet the probability of an earthquake during the next year or even during the next decade is relatively small, even in high seismic areas. Does it make sense, then, for a utility to invest in a new or retrofitted facility? In assessing the cost and benefits of such an investment, a utility needs to consider the consequences of failure, including the impact on neighbors who may be flooded and on a community that might be devastated due to failure of a tank or reservoir. Often, small operational changes or small retrofit projects can mitigate a large portion of the risk. Table 3.7 (next page) summarizes common tank and reservoir vulnerabilities, their effects, and possible mitigations.

90 Answers to Challenging Infrastructure Management Questions Table 3.7 Tank/Reservoir Seismic Vulnerabilities Seismic Vulnerability Associated Risks Mitigation Strategies Rigid pipe connections through walls or floor of tank Height/diameter ratio creates risk of overturning or elephants foot buckling 60 Roof structure not adequately connected to walls or not adequately braced Inadequate free board 61 for water wave generated by seismic motions Rocking and lateral movements of the tank result in rupture of the tank wall or floor, or breakage of the pipe Catastrophic loss of facility and its contents Collapse of roof into tank Damage to roof and upper walls of tank Possible spillage from the top Provide a flexible connection between the pipe and the tank Operate tank at reduced water level, except in times of very high demands Retrofit with anchors or annular plates to resist overturning Connect roof to walls and add seismic bracing Operate tank at reduced water level Inadequate flood containment Tank overflow or rupture endangers adjacent and downhill properties Berms and drainage facilities to confine and convey water 60 Elephants foot buckling is a buckling of the lower wall of a steel tank, produced by a combination of hoop stress and vertical compression. In fortunate cases, tank integrity remains, but a risk of rupture exists, particularly between the wall and base plates. 61 Freeboard is the difference in elevation between the overflow or spillway and the roof

CHAPTER 4 - WATER QUALITY AND INTERNAL CORROSION The quality of the water affects the longevity and integrity of the infrastructure. Conversely, the quality of the infrastructure has significant effects on the quality of the water at the customer s tap. A great deal of research by the WaterRF and others has been devoted to this subject. This chapter skims the surface of this research as it relates to overall infrastructure management. For concerns about lead, copper, and other health issues, other reports should be consulted. For many years, the water community focused on the quality of water leaving the treatment plant. Concerns about parasites, viruses, bacteria, heavy metals, carcinogens and other contaminants led to ever more sophisticated analysis and treatment of source waters. In recent years, more focus has turned to distribution systems, with the realization that pristine water leaving the treatment plant can be far from pure at the taps of many customers. Regulatory compliance is a concern, as well as meeting customer expectations. Water discoloration is a major reason for customer complaints for many utilities. From the customer s perspective, the quality of the distribution system affects: The aesthetic qualities of the water delivered to the tap The pressure at which the water is delivered The reliability of service The service life of the household plumbing From the utility s perspective, the quality of the distribution systems affects: The healthful properties of the water delivered to the tap The ability to comply with regulations The cost of water delivery, including pumping costs The flows available to fight fire and meet peak demands The cost of maintaining the system and keeping it operating The longevity of pipes and other infrastructure HOW DO I ASSURE THAT GOOD QUALITY WATER ARRIVES AT THE TAP? Good infrastructure management is part of the multi-barrier approach to assuring that water delivered to customers is safe and not objectionable. In a perfect system, pipes and other materials contacting the water are tested and certified in accordance with the requirements of ANSI/NSF 61, are smooth and clear of sediment, do not leak and do not break. In the real world, many of our systems have old leaking pipes, constructed of materials that corrode and leach contaminants into the water, and accumulate tuberculation and sediment harboring bacteria. Figure 4.1 shows an extreme example. These pipes represent risks to the utility and its customers. 91

92 Answers to Challenging Infrastructure Management Questions Figure 4.1. Heavily scaled 80-year old cast-iron main. Risks associated with poor infrastructure include: Increase risks of pathogen entry during main break repairs Risks of pathogen entry from a combination of negative pressure during transients and pipeline leaks Depletion of disinfectant due to interaction with materials, sediments, and biofilms Accumulation of sediments within corroded and scaled pipes and associated problems with water discoloration and biofilm growth Adverse health conditions due to leaching of lead and copper from service lines and meter brass components Episodic releases of contaminants accumulated within scales, due to changes in water chemistry or operations Each of these risks can be reduced through an infrastructure management plan that includes: Monitoring and modeling the changes in water quality as it moves through the system, to help in developing operational and capital plans Mains cleaning programs that regularly remove sediment from the system, particularly from unlined cast iron mains Pipeline rehabilitation programs geared towards cleaning and lining all unlined cast iron pipes that are not scheduled for replacement Infrastructure renewal programs that keep the frequency of breaks and the number of leaks at a moderate, manageable level A plan for lead and copper reduction, as needed to achieve regulatory compliance and meet public health goals, which may include use of corrosion inhibitors, replacement of lead services lines, and other strategies Reduction and control of lead and copper in drinking water is a very complex subject, and the WaterRF website is a good source of information. The link below provides a good overview of lead and copper issues, as of January, 2013:

Chapter 4 Water Quality and Internal Corrosion 93 http://waterrf.org/resources/lists/publicspecialreports/attachments/9/leadcorrosion.pdf ARE HEALTH ISSUES ASSOCIATED WITH DIRTY WATER EVENTS? The accumulated residue in an unlined 8-inch diameter cast iron pipe can easily exceed two tons dry-weight per mile of pipeline. This residue is composed primarily of iron hydroxides and allied minerals that have high affinity to arsenic, uranium, lead and other materials of concern. The solids that develop in a distribution system thus can gradually become enriched with those contaminants. Sudden releases of these contaminants occurs from chemical or hydraulic changes, resulting in spikes in concentrations. Figure 4.2 illustrates how iron-based corrosion scale accumulates and releases organic material. Previously, inorganic contaminants (other than lead, iron, and copper) were thought to remain essentially constant as water passed through the system; their behavior would be termed conservative in the chemistry sense. However, recent investigations by Friedman et al., (2010) cast doubts on any presumption of conservative behavior by these potentially harmful inorganic contaminants. Evidence now shows that some consumers are likely exposed to undesirable contaminants that are not currently caught in the monitoring framework. Source: HDR Figure 4.2. Accumulation and release of distribution system contaminants. All of these processes can be occurring simultaneously. Common factors that lead to the chemical release of accumulated contaminants include changes in chemical additives, including sequestrants, disinfectants, and corrosion inhibitors. Examples include: The addition of sequestering agents can dissolve iron and other minerals that help stabilize the scales, making them more susceptible to scour Introducing disinfection into an existing system that has not been previously disinfected can likewise release contaminants. The disinfectant may change the oxidation/reduction potential (ORP) in the distribution system, which may affect the sorptive capacity and selectivity of the scale for certain contaminants. The addition of chlorine to the previously unchlorinated groundwater can also affect the composition and stability of corrosion scales on residential copper plumbing, resulting in a release of copper oxide particles and arsenic sorbed to them (Reiber and Dostal, 2000).

94 Answers to Challenging Infrastructure Management Questions WHAT MAKES WATER AGGRESSIVE 62? As discussed in Chapter 3, the integrity and longevity of metallic and AC pipes are very much affected by the chemistry of the water. This is also true of concrete and mortar lined pipes, but to a lesser degree. The parameters that influence the aggressiveness of water are summarized in Table 4.1. Table 4.1 Factors Which Affect Water Corrosivity More Aggressive Less Aggressive ph Low (<7.5), acidic High (>7.5), basic Dissolved Oxygen High (>0.3 mg/l) Low (<0.3 mg/l) TDS High (>500 mg/l), increases conductivity Low (<500 mg/l) Alkalinity Low (<30 mg/l, as CaCO 3 ) High (>30 mg/l, as CaCO 3 ) Calcium Hardness Low levels (<30 mg/l) can leach lime from concrete pipe, AC pipe, and cement mortar linings High levels (>30 mg/l) provide protective films on metal, concrete, AC, and mortar-lined pipes. Silica Low High levels can provide a protective film Polyphosphates High levels of polyphosphate promotes softening of cementitious materials High levels generally promote protective film formation High levels sequester ions (e.g., iron and manganese) that promote corrosion or cause water discolration Orthophosphates Uniformly beneficial at reducing the solubility of metals leaching from plumbing materials, including lead, copper, zinc, tin and iron. Temperature High temperatures increase the rate of corrosion (continued) 62 The term aggressive has been used for many years in the industry to connote water that quickly degrades pipes, and is synonymous with corrosive, if corrosion is broadly defined as material degradation in response to its environment. Both terms are used in this report.

Chapter 4 Water Quality and Internal Corrosion 95 Table 4.1 Factors Which Affect Water Corrosivity More Aggressive Water Flow in Pipe High velocities provide more oxygen to metal surfaces High velocities and turbulence remove protective films and scales Stagnant water (<0.5 FPS) can lead to non-homogenous electrolyte Chlorine May remove protective biofilms Chlorine is a strong oxidizing agent Sulfate Can form mineral acids (>300 mg/l) Promotes sulfate reducing bacteria Is deleterious to AC, cement mortar and concrete CO2 High levels are corrosive, particularly to cementitious materials Total Inorganic Carbon Low levels are corrosive to cementitious materials H 2 S High levels (>0.1 mg/l) corrosive to ferrous and cementitious materials Sulfide is a known cause of rapid pitting on copper and copper alloys Less Aggressive Moderate flows (Continued) May kill microorganisms that catalyze corrosion Helps establish insulating corrosion film layer in copper pipe Speculated to minimize corrosion on some brass alloys.

96 Answers to Challenging Infrastructure Management Questions WITH ALL THOSE FACTORS, HOW CAN I TELL WHETHER MY WATER IS AGGRESSIVE? The interplay of these variables determines whether a utility s water is aggressive or not. Various indices have been derived to help judge whether water is corrosive, but no single index works in all cases. The Langelier Index (LI) is the most widely used method for evaluating whether water is aggressive. The LI is calculated from ph, alkalinity, calcium, temperature, and ionic strength. 63 A positive number indicates non-corrosive water water that will deposit CaCO 3 within the pipe. However, despite its popularity, some researchers have expressed reservations. Studies dating back to 1957 have demonstrated that the bulk water LI may be an unreliable indicator of corrosiveness (Benjamin et al. 1996). A fair amount of research has indicated that buffer capacity may be a more important index for determining water corrosivity. Buffer capacity is defined as the resistance of a solution to ph change, when a strong acid or base is added. A high buffer capacity maintains the ph at the pipe wall close to the ph in the bulk solution. Where buffer capacity is low, corrosion reactions near the metal surface can change the ph at the metal surface. This is perhaps why the bulk water LI is sometimes unreliable. The LI at the metal surface can be considerably different than the LI for the bulk water, if the buffer capacity is low. Calcium carbonate precipitation potential (CCPP), is another index that is frequently employed. CCPP measures the amount of CaCO 3 that will precipitate at equilibrium. Again, the rationale being that a minor amount of CaCO 3 deposition (scale formation) is protective of the corroding surface While buffer capacity may be the most useful measure of corrosiveness, there are insufficient data to indicate that it can be used as a sole index. All three indices should probably be considered. The aggressiveness of water can also be determined in other ways by observing the affect on pipes that have been in use for some time, by determining changes in the quality of the water as it moves through the system, by performing coupon studies, or by performing pipe loop studies. 64 CAN THE CORROSIVITY OF THE WATER BE MEASURED? One standard test for determining the corrosivity of water is the loop test, where water is circulated through pipes and changes in water chemistry are measured. A similar test involves the use of two circular vessels, one inside the other. The annulus between the vessels is filled with water and one vessel rotates. While neither technique is a direct measure of corrosion, both provide a measure of metal leaching as a result of corrosion, and both are very sensitive to changes in water chemistry. However, neither of these methods is successful in detecting localized forms of corrosion (pitting), which may not be a health concern, per se, but lead to damage to plumbing systems in homes and businesses. Project 2648, Optimizing Corrosion Control in Water Distribution Systems (Duranceau, et al., 2004) investigated the use of a multi-element sensor, electrochemical technique for 63 A modified version of the Langelier Index known as the Aggressiveness Index is often used for AC pipe. 64 Coupon tests involve immersing precisely weighed coupons in the water and determining metal loss over time. In a closed loop system, a known volume of water is circulated through a section of pipe, and the concentration of metal taken up by the water is measured over time.

Chapter 4 Water Quality and Internal Corrosion 97 instantaneously monitoring corrosion and optimizing corrosion control. By analyzing electrochemical noise (ECN), these probes appeared capable of measuring low rates of pitting attack in addition to general corrosion. Online probes were used to monitor corrosion of steel, copper, and lead-soldered electrodes in untreated and inhibited water. EN corrosion rate calculations appeared to follow changes in process parameters such as the introduction of inhibitors, water flow rates past the electrodes, and water temperature. A later study, Project 3109, Non-Uniform Corrosion in Copper Piping Monitoring Techniques (Edwards, et al., 2009) evaluated the accuracy of several electrochemical monitoring techniques (ECorr rise, ECN, and pit wires) for predicting the propensity for copper pitting in potable water. This study was unable to demonstrate the usefulness of any of these techniques. SHOULD THE WATER BE CONDITIONED SO IT S LESS AGGRESSIVE? The first thing to consider is how the corrosivity of the water is affecting the quality of the water at the tap. The chief concern is health. Internal corrosion of the pipes can lead to several problems, the most serious being excessive lead in the water. Lead leaches from service pipes, pipe joint material, pipe soldier, and brass throughout the system. The health affects are serious and well documented. Similar leaching occurs with copper and other metals of concern. Aggressive water can also leach calcium from cementitious materials, producing excessively high ph at the tap, weakening of cement mortar, loss of steel and iron corrosion protection, and weakening of AC pipe. Water quality aesthetics may also be affected; internal pipe corrosion can lead to a whole rainbow of problems water that comes out red, brown, black, or blue. This discoloration is both unappetizing and damaging damaging to laundry, porcelain fixtures, and a utility s reputation. On top of this, aggressive water also weakens the pipes. Deciding whether to condition aggressive water is both a regulatory issue and a judgment call. The Lead and Copper Rule requires utilities to treat water where more that 10 percent of customers are receiving water at the tap with a lead content in excess of 0.015 mg/l or a copper content in excess of 1.3 mg/l. However, utilities can certainly take action that is not mandated, to improve the healthful and aesthetic qualities of the water. Conditioning aggressive water can make economic sense as well, by helping preserve the distribution and plumbing assets of the utility and its customers. One study found benefit/cost ratios that exceeded 5:1 in favor of treatment (Ryder, 1980). Interestingly, most of the economic benefits from water conditioning occur on the customer s side of the meter, in extending the lives of the plumbing and service lines. A WaterRF study recommended investigating the economics of water conditioning in any systems where the average life expectancy of cast-iron pipes was less than 75 years. 65 Conditioning of water can be done in a number of ways, and testing is often required to find the best treatment for a particular system. General methods fall into four categories: ph elevation/alkalinity adjustment Calcium carbonate saturation Orthophosphate or polyphosphate corrosion inhibitors Silicate corrosion inhibitors 65 Economic and Engineering Services, Inc. and Kennedy/Jenks/Chilton, Inc., 1989. This publication contains a step-by-step method for performing an economic analysis.

98 Answers to Challenging Infrastructure Management Questions Whether and how to condition water to reduce its aggressiveness are complicated issues, hinging on the qualities of the water and the types of materials in the system. 66 The effects on cast iron and steel will be different than on concrete and AC. The effects of water conditioning on the qualities of wastewater effluent may also need to be considered. Project 3127, Examining the Impact of Water Quality on the Integrity of Distribution Infrastructure (Sadiq, et al., 2007) found that the water properties which best favored iron pipes were not always favorable to copper pipes. Increasing the amount of chlorine to kill pathogenic microorganisms can cause deterioration in some pipe materials. Project 3107, Effect of Changing Disinfectants on Distribution System Lead and Copper Release (Boyd, et al., 2010) found that lead-bearing materials (lead and bronze) were affected primarily by background water quality conditions (i.e., changes in ph, alkalinity, or phosphate addition) rather than changes in disinfectant. Copper materials (copper and bronze pipe loops) were sensitive to the presence of a disinfectant (free chlorine or chloramines) but the observed effects were transient and not necessarily related to a higher aggressivity of free chlorine vs. chloramines. WHAT CORROSION INHIBITORS WORK BEST FOR COPPER AND LEAD? Project #2587, Role of Phosphate Inhibitors in Mitigating Lead and Copper Corrosion (Edwards and Holm 2001) determined that orthophosphate decreased concentrations of soluble lead and copper, whereas polyphosphate increased concentrations of soluble lead and copper through complexation reactions. The latter is consistent with expectations based on solubility models. Particulate corrosion by-products are very important, especially when considering control of lead from pure pipe materials. The results call into question use of hexametaphosphate or other polyphosphates for corrosion control, especially for lead and copper. This 4-year study was based on controlled laboratory experiments with no inhibitors, orthophosphate, and polyphosphate, using pure lead and copper pipes. Project #4103, Comparison of Zinc vs. Non-Zinc Corrosion Control for Lead and Copper (Schneider et al., 2011) found that for general corrosion of lead and copper in most locations, there did not appear to be a significant difference in performance between zinc orthophosphate (ZOP) and non-zop. However, for soft water, it appeared that ZOP may be beneficial for cementitious constituents of the system. Project #4064, Influence of Water Chemistry on the Dissolution and Transformation Rates of Lead Corrosion Product (Giammar et al. 2010), determined that the effectiveness of corrosion control depends on not just source water chemistry but also the composition of pipe scales. For pipe scales with significant amounts of the lead (IV) oxides plattnerite or scrutinyite, low lead concentrations were achieved when a free chlorine residual was maintained. Less lead was released at higher ph values. The dissolution of hydrocerussite, which is a frequently observed corrosion product, was also slower at high ph. While increasing the water s alkalinity can help in achieving stable higher ph values, associated increases in dissolved inorganic carbon can increase the rates of lead release from plattnerite. Complex effects on hydrocerussite dissolution were also seen. The addition of orthophosphate dramatically decreased the rates of lead release from both plattnerite and hydrocerussite surfaces. 66 Edwards and Reiber 1997 is useful in investigating treatment methods. Software is provided with this WaterRF publication that aids the decision process.

Chapter 4 Water Quality and Internal Corrosion 99 WHAT CORROSION INHIBITORS WORK BEST FOR CEMENT MORTAR LININGS, AC PIPE, AND OTHER CONCRETE PIPE? Project 4033, Impact of Phosphate Corrosion Inhibitors on Cement-Based Pipes and Linings (Atassi et al., 2009) found that both non-zinc-based phosphate inhibitors (orthophosphate and polyphosphate) were effective at reducing concrete corrosion at near neutral ph, but at a ph of 8.3 neither orthophosphate nor polyphosphate were effective at reducing corrosion. On the other hand, the addition of 0.25 mg/l Zn produced a 33 percent reduction (in comparison to control) in calcium leaching relative to use of orthophosphate alone. Likewise, Project 4103 (Schneider, et al., 2011) found that, for soft water, zinc orthophosphate is highly beneficial for cementitious constituents of the system. DOES THE USE OF CORROSION INHIBITORS HAVE ANY DELETERIOUS SIDE EFFECTS? A sometimes unanticipated side effect of adding phosphate-based corrosion inhibitors is a slight, but measureable, increase in phosphorous loading on treatment plants receiving the domestic wastewater. Due to substantial inherent phosphorous content of domestic wastewater (5-10 mg/l as P), the marginal increase due to a corrosion inhibitor is generally irrelevant to wastewater plant performance and discharge. But because wastewater plants are being called on to meet increasingly more stringent effluent nutrient limitations in some cases the phosphorous is limited to 1 mg/l the addition of a phosphorous corrosion inhibitor must be strictly controlled and coordinated with the wastewater utility. Phosphate also sometimes plays a role in determining where, when, and if problems with nitrification will occur in a distribution system. High levels of phosphate inhibitor make nitrification more likely. Nitrification, in addition to creating a variety of aesthetic and disinfection issues, may increase lead contamination of low alkalinity potable water by reducing ph and, hence, increasing lead solubility. The possibility of nitrification should not preclude the use of phosphate corrosion inhibitors, but it is an important operational consideration for systems that use chloramine. WHAT'S THE BEST WAY TO REDUCE LEAD? If the lead comes from the service lateral, Project 3018, Contribution of Service Line and Plumbing Fixtures to Lead and Copper Rule Compliance Issues (Sandvig, et al., 2008) found the most effective way to reduce the total mass of lead measured at a household tap was to replace the entire lead service line. The project went on to identify techniques for the rehabilitation or replacement of service laterals, including open-trench replacement, slip lining, and pipe coating. Twenty-eight techniques are identified ranging from proven (open trench replacement) to experimental (wax coatings) and cross-over techniques (from gas and wastewater operations). Replacement of faucets and end-use fittings may be warranted at sites without lead service lines, assuming that optimized corrosion control has failed to reduce elevated lead levels in first draw samples. For system-wide lead reduction, two decades of experience with the Lead and Copper Rule has shown that phosphate-based corrosion inhibitors are effective at reducing lead release from domestic plumbing surfaces (Brown, et al., 2012). Utility experience strongly suggests that

100 Answers to Challenging Infrastructure Management Questions a very modest addition of phosphate inhibitor is highly beneficial, and one of the most costeffective and easily implemented water quality control measures for lead control. However, there is a target water quality window (ph and alkalinity range) that limits the beneficial use of phosphate corrosion inhibitors. Moreover, not all phosphate inhibitors are created equal; simple orthophosphates are more effective on a mass basis than blended or pure polyphosphate compounds relative to metal release. The adjustment of ph can also be both effective and is sometimes necessary for control of lead. However, in many, if not most circumstances, orthophosphate addition is the most costeffective alternative, easier to implement, producing better results. If a utility serves residential areas with older homes and an abundance of lead bearing plumbing fixtures, and/or lead service lines, orthophosphate addition must be considered the preferred alternative. Orthophosphate addition is only appropriate within a ph and alkalinity window; hence, sometimes both orthophosphate addition and ph control are necessary. DOES PARTIAL LEAD SERVICE LINE REPLACEMENT (PLSR) MAKE SENSE? When a utility replaces the lead service line that it owns (up to the property line or meter), but leaves in place the lead service line owned by the customer, this is termed a partial lead service line replacement (PSLR). The general preference would be to remove the entire lead service line (LSL), but homeowners are often either unwilling or unable to pay for the removal of the portion of the line they own. PLSR is the fallback position required by law. PLSRs are unpopular with both regulators and utilities. They only remove a portion of the lead source, which makes the cost difficult to justify, and there is considerable controversy regarding the whether a positive benefit is derived. Even though the goal of a PLSR is to reduce lead, some evidence suggests that galvanic action between the old customer-owned lead pipe and the new utility-owned copper pipe may actually increase lead release, when the two metals are directly connected via metallic coupling. This issue has received considerable research attention, yet remains complex and contentious. Field data have shown inconsistent lead release responses to PLSRs; increases and reductions have both been observed. Observations of lead release associated with field installed PLSRs (Cu/Pb couples) in several cities (Sandvig, et al., 2008) indicate that in many circumstances PLSRs do not produce long-term increase in lead release. In instances where temporary elevated lead levels have been observed, it is not clear whether this was the result of electrochemical action, or the mechanical disturbance of the existing LSL and subsequent release of lead scale particulates. For an overview of the latest research, readers are directed to the WaterRF website. No utility has studied PLSRs and LSLs longer than DC Water. The DC Water data base on PLSRs and LSLs extends to over a hundred homes sampled yearly for a period of seven years (Edwards, 2012). Their data suggest that lead release on PLSRs in service less than a year is statistically comparable to lead release on undisturbed LSLs (both for median and 90 th percentile values). While not indicating a galvanic corrosion problem, this would suggest that the PLSR provides little value in reducing household lead exposure. However, the DC Water data sets also show that PLSRs in service longer than a year release lead at levels meaningfully lower than the undisturbed LSLs, suggesting that in the long-term, PLSRs do provide a lead abatement benefit. While somewhat controversial, these data only underscore the point that if a PLSR can reduce lead exposure at all, then the removal of the full LSL should be the desired objective.

Chapter 4 Water Quality and Internal Corrosion 101 SHOULD WATER MAINS BE CLEANED? Pipe cleaning removes sediment and biofilm from pipes, reducing the risk of water discoloration, taste and odor problems, coliform regrowth, and regulatory non-compliance. Aggressive pipe cleaning can also remove scale and tuberculation, dramatically improving hydraulic capacity. However, aggressive cleaning without lining may remove protective scales from pipe walls, increasing the corrosion rate, depleting chlorine, and worsening water discoloration. HOW SHOULD PIPES BE CLEANED? Project #2688, Investigation of Pipe Cleaning Methods (Ellison 2003) investigated common cleaning methods used for water mains, comparing the methods in terms of cost and effectiveness in removing sediment, biofilm and scales. Table 4.2 provides a summary. Conventional Flushing Table 4.2 Comparison of Common Water Main Cleaning Methods Cost Rank Removes Comments Lowest Contaminated water Only recommended for emergencies Unidirectional Flushing 2 Sediment and some biofilm Generally only useful on small mains (12-inches or smaller) Air Scouring 3 Sediment, some biofilm, and friable scales Limited use in North America. Swabbing or Poly Pigging 4 Sediment, biofilm, and soft scales Bypass system may be needed and launching/receiving ports Abrasive Pigging 5 Sediment, biofilm, and all scales Bypass system may be needed and launching/receiving ports Mechanical Cleaning and Lining Highest Sediment, biofilm, and all scales Provides long-term solution and possible structural benefits. Unidirectional Flushing Nearly all utilities occasionally flush portions of their systems, often in reaction to customer complaints, to raise chlorine residuals and to remove turbid and other poor-quality water. Unidirectional flushing is a proactive, planned, systematic method of flushing the system, starting from the water source and moving outward. Selected valves are closed and hydrants are opened in a sequence so that water flows in one direction through the mains (Figure 4.3). This increases the flushing velocities and more effectively confines and expels sediments from the

102 Answers to Challenging Infrastructure Management Questions system. Conventional flushing (non-unidirectional), on the other hand, can stir up sediment in the general area, and increase customer complaints. HYDRANT CLOSED VALVE HYDRANT WATER MAIN FLOW FLOW FLOW FROM PREVIOSLY CLEANED PIPE CONVENTIONAL FLUSHING UNIDIRECTIONAL FLUSHING Source: Ellison 2003 Figure 4.3. Comparison of conventional and unidirectional flushing techniques Figure 3.1 When properly performed, unidirectional flushing has been shown to result in reductions in turbidity, color, iron, HPC 67 bacteria, and customer complaints. The effectiveness of the method depends on the flushing velocities that are achieved. A minimum of 3 feet per second is needed, but 5 feet per second is better. In large diameter mains, achieving these velocities may not be possible because of hydrant restrictions and water disposal concerns. Where mains are heavily scaled, flushing alone is not sufficient to lift and remove sediment and biofilm from deep recesses in the scale. Air Scouring Air scouring (Figure 4.4), a method used in the UK, New Zealand and Australia, involves a mixture of air and water. It is similar to unidirectional flushing, except the fluid column is 75 percent air, which reduces the friction and causes the slugs of water to move very quickly and with great turbulence. It is the water, not the air, that actually does the cleaning. Certain precautions are needed to assure that the air does not contaminate the pipe, particularly with oil from the compressor. 67 Heterotrophic plate count

Chapter 4 Water Quality and Internal Corrosion 103 Source: Ellison 2003 Figure 4.4. Air scouring Ice Pigging A new method, ice pigging, was introduced to North America in 2012 and uses a slurry ( slush ) mixture of water and crushed ice for flushing mains. The slurry is pumped through the system between a pair of fire hydrants, cleaning a valved-off section of main. This method appears to be fairly effective at removing sediment, particularly from heavily scaled pipe. It offers the additional advantage of being adjustable; by varying the proportion of ice in the slurry, the degree of abrasion and scour on the pipe surface can be controlled. This can be important when it is not desirable to remove the entire corrosion scale and risk exposing bare metal. Swabbing and Pigging A wide range of cleaning results can be achieved with swabbing and pigging, depending on the number, size, and design of the pigs used (Figure 4.5). A swab is simply a soft-foam pig. In some instances, pigs can be introduced and extracted via hydrants, but more commonly, launching and receiving ports are needed. Cleaning to bare metal can be achieved, but such aggressive cleaning can exacerbate water quality problems by accelerating the corrosion of the metal.

104 Answers to Challenging Infrastructure Management Questions Source: Pipeline Pigging Products, Inc. Figure 4.5. Pipe cleaning pigs Cleaning and Lining In-situ cleaning and lining with cement mortar has been practiced to some extent since the 1920s, and specialty contractors rehabilitate thousands of miles of water main each year, using mortar, polymer, and other linings. A more complete description of available methods is found in Chapter 6. Other Cleaning Methods Several pipe cleaning methods developed for other purposes have been occasionally applied in water mains. These include water-jet cleaning and chemical cleaning. The 2002 WaterRF project found no particular benefits and several liabilities when these methods were used in water mains. HOW OFTEN SHOULD A SYSTEM BE FLUSHED? Nearly all mains need cleaning eventually. Sediments accumulate, biofilms grow, scales develop, and water quality deteriorates in processes that promote one another. As this occurs, customer complaints increase, hydraulic capacities decrease, and the risks of coliform regrowth and other water quality problems rise. The frequency of cleaning really depends upon how quickly sediment accumulates. The greatest source of sediment is generally the pipes themselves, particularly any unlined cast iron pipes in the system. However, sediment can come from unfiltered surface water, wells, and the oxidation of dissolved iron and manganese. Many utilities flush their mains annually, but the 2003 cleaning methods study showed that some utilities could show no significant benefit for this effort, whereas as for other utilities, no amount of flushing could alleviate chronic problems cause by unlined cast iron mains. The

Chapter 4 Water Quality and Internal Corrosion 105 conclusion of the study was that the benefits of flushing should be gauged by taking water samples from customer taps or sampling stations (not from the hydrants) and that these measurements should be used for determining the frequency of flushing. HOW CAN I DIAGNOSE A WATER QUALITY COMPLAINT? Figure 4.6 (following page) provides a diagnostic chart for common water distribution problems. Flushing is often the first and most economical response to many of these problems, and it can often be quite effective. But sometimes a flushing reaction makes things worse, by spreading contamination throughout the system and stirring up sediment. Moreover, for many problems, flushing provides only a short-term solution. To prevent problems from recurring, a more comprehensive approach may be needed, using a combination of pipe cleaning and system improvements. The biggest cause of dirty pipe in most systems is corrosion of the pipe itself. Within pipes, iron oxides are the predominant minerals found in sediment, while in tanks and reservoirs, natural sands and silts are more common (Block, et al., 1996). Another significant cause of dirty pipe is groundwater; either due to the oxidation of dissolved iron and manganese or the deposition of natural sediments pumped from wells. Whether the sediment comes from corrosion of the pipe, or from groundwater, flushing the system to remove the dirty water and sediments provides only a temporary fix. The problem will be expected to return as long as the pipes remain unlined, or the water source remains unfiltered. Not all dirty water is caused by events within the utility system. The cause of many red and brown water complaints is the steel and iron pipes on the customer s side of the meter. No amount of flushing or cleaning of the distribution piping can relieve these problems; however, water conditioning can reduce corrosion-caused water discoloration that occurs on both sides of the meter. WHAT CAUSES DEPLETION OF DISINFECTANT IN THE SYSTEM? Project 2849, Disinfectant Decay and Corrosion: Laboratory and Field Studies (DiGiano et al., 2004) studied disinfectant decay and corrosion in both the laboratory and field and concluded that a zero-order rate model described the overall chlorine decay rate for cast-iron pipe, for a range of initial chlorine concentrations, ph, chloride concentration, and dissolved oxygen concentrations. The chlorine decay rate increased with higher velocity (due to higher mass transfer at the pipe surface), lower ph (due to faster corrosion rate), and lower DO (due to greater release of Fe 2+ after removal of the oxidized layer at the surface). Increasing the chloride concentration greatly increased the underlying corrosion rate of the pipe wall, but did not produce an immediate increase in the chlorine consumption rate coefficient, thus, indicating the ongoing corrosion rate on the pipe surface is not necessarily a predictor of wall/water interactions.

106 Answers to Challenging Infrastructure Management Questions Source: Ellison 2003 Figure 4.6. Diagnostic chart for distribution water quality issues

Chapter 4 Water Quality and Internal Corrosion 107 WHAT CAUSES PITTING ON COPPER SERVICE LINES AND DOMESTIC PLUMBING? Copper pitting is the process whereby rapid localized corrosion can perforate conventional copper tubing within a few months to several years. Although not a new phenomenon, copper pitting has become the focus of recent litigation brought against utilities wherein plaintiffs claim that the chemistry of the delivered water was the direct cause of pitting, subsequent leakage and household damage. The pitting and penetration of copper tubing remains a poorly understood process, and while rare, it is common enough to generate substantial technical discussion and internet discussion. It is generally agreed that there can be multiple causes, and that the mechanism, morphology and mineralogy (corrosion scale) associated with pitting can vary substantially from one venue to the next (Edwards, et al., 1994). The Copper Development Association (CDA, 2012) lists the three most common causes of copper tubing failure as: Erosion Corrosion - excessive water velocities resulting in scouring and erosion of plumbing surfaces Flux-Induced Corrosion - fabrication issue related to excessive use of an acidic paste (flux) in the joint soldering process, Concentration Cell Corrosion - corrosion that occurs underneath mineral sediment and often related to hot water heater sediment. There are other recognized causes, including forms of microbial action that generate sulfides (Microbially Influenced Corrosion (MIC)), and water quality related causes associated with extremes of ph and/or alkalinity. Other proposed causes are more speculative. Laboratory studies have indicated that in some cases pitting can be initiated and propagated by aluminum based deposits that are theorized to catalyze the reduction of chlorine disinfectants and accelerate oxidation of the tubing wall underlying the deposit (Marshal, et al., 2013). This theory has been the basis of ongoing litigation claiming utilities distributing water with more than 50 ppb of total aluminum and a relatively high ph are guilty of a breach of implied warranty - supposedly because they are distributing a product they know, or should know, is damaging to their customer s pipes (DC WASA, 2009). Regardless of cause, the failure of copper tubing is rare, and copper remains the material of choice for a large portion of today s commercial and residential plumbing installations thanks to its strength and durability. A utility s first response to claims of copper pitting should be that of investigation and documentation. Often, it will be found that the copper pitting is not attributable to water quality, but more likely relates to problems of workmanship, hot water recirculation, or sediment carryover from the hot water heater. Any proposed changes to water treatment to deal with copper pitting should be carefully considered. Dosing with a phosphate-based corrosion inhibitor is the only recommended strategy for mitigation of significant outbreaks or widespread problems of copper pitting (WSSC, 2008).

108 Answers to Challenging Infrastructure Management Questions WHAT CREATES BLUE WATER? HOW CAN IT BE ELIMINATED? Project #4164, Lead and Copper Corrosion Control in New Construction (Edwards et al., 2011) found that changing from chlorine to chloramine hindered the passivation of newer copper pipes in a few cases. The result is that some neighborhoods of newer homes had persistent problems with blue water and blue staining due to high copper leaching. These problems can be overcome by using free chlorine for initial disinfection of the plumbing, followed by a thorough flushing to remove soldering flux and any sediment. Inadequate flushing of soldering flux from a new plumbing system can lead to the proliferation of nitrifying bacteria. Nitrification will generate higher levels of microbial growth, suppressing the ph of the water and create higher levels of lead and copper at the tap (Zhang, 2009). If chloramine is not adequately controlled in the system, or if stagnation occurs locally, nitrification occurs, which increases the lead and copper measured at the tap. If a system-wide problem exists, increasing the ph of the distributed water, boosting the chlorine in certain areas, mixing the water in storage tanks, or adding a phosphate corrosion inhibitor (separately or in combination with ph adjustment) may be beneficial in reducing the frequency of blue water complaints. The redox condition (Oxidation Reduction Potential) of the distributed water is usually a strong function of chlorine and dissolved oxygen levels. When those levels are diminished, the resulting chemical environment (reducing) can destabilize corrosion scales and enhance the solubility of scale components. Water sitting stagnant in household plumbing will eventually lose its disinfectant residual, leading to increased cuprosolvency, resulting in blue water. Homes that have been empty (plumbing unused) for periods of a month or more often experience colored water and microbial issues. Perhaps counter intuitively, the presence of an oxidizing compound such as chlorine is actually useful for minimizing copper corrosion by enhancing the stability of the passivating scales that protect the underlying metal. HAS SIMULTANEOUS COMPLIANCE WITH VARIOUS REGULATIONS (DBP AND TCR) ADVERSELY INFLUENCED CORROSION CONTROL? At one time there was considerable concern that achieving compliance with the LCR would adversely affect a system s status vis-à-vis other regulations, primarily the Disinfection Byproduct Rule. The kinetics of DBP formation are influenced by ph, and under some circumstances corrosion control measures (ph and alkalinity modification) may have a minor impact on overall trihalomethane formation (Benjamin, et al., 1998). In practice this has not been a serious issue; few utilities have reported meaningful interference with a DBP control program as a result of LCR compliance efforts. On the other hand, efforts to minimize DBP formation through the use of enhanced coagulation techniques and the use of polymerized aluminum coagulants has led to reports of increased lead release from domestic plumbing fittings. Changing coagulants from conventional alum to a polyaluminum chloride (PACl) will in some cases change the effective chloride/sulfate mass ratio (CSMR) of the distributed water. Recent literature suggests that increases in the CSMR may have meaningful impact on lead release from soldered joints and leaded brass faucets (these surfaces are supposedly vulnerable because of galvanic action) (Triantafyllidou, 2008). While there is laboratory-based research to support the CSMR hypothesis, actual field

Chapter 4 Water Quality and Internal Corrosion 109 data and utility experience is mixed. For utilities anticipating a change in coagulant regimen, a cautious assessment of the CSMR hypothesis is as follows: CSMR may be relevant in waters with low background chloride levels Alkalinity (buffer capacity) is likely important because of localized ph effects. (Increased use of coagulants may decrease the alkalinity of the finished water and also diminish buffering capacity, making the water more susceptible to ph variations.) The re-equilibration effect is likely important. (Re-equilibration is the corrosion effect produced by forcing old and stable corrosion scales to come to equilibrium with a new water chemistry this often results in metals release from the old scale.) Galvanic effects are likely of minor importance Phosphates are marginally effective at minimizing the supposed CSMR effect WHAT ARE THE UTILITY S OBLIGATIONS IN RESPONDING TO CUSTOMER WATER QUALITY AND CORROSION COMPLAINTS? There are few standards of care (SOCs) detailing a utility s responsibilities to its customers. However, the water industry is making strides in codifying generally accepted practices and procedures and developing recognized SOCs. The progress made on the recently updated AWWA Standard G200 Series ( Distribution Systems Operation and Management ) is such an example. It better defines the utility obligations to customers, including proper handling of customer complaints relative to water quality and corrosion. The G200 defines some minimum requirements: Log keeping Complaint investigation Spatial and temporal complaint mapping Customer reporting Utilities that do not follow a clear and documented policy with respect to customer complaints leave themselves open to charges of indifference, and possible negligence. HOW DOES A UTILITY PROTECT ITSELF FROM LITIGATION? Courts and legislatures in many states have greatly restricted, and in some cases have abolished, the doctrine of governmental tort immunity. A utility can be a tempting high-profile target, for no other reason than the rate-payers represents a large, ready-made class. The formation of a class, with the potential for an aggregate payout, is what plaintiffs lawyers seek. While no utility can be judgment-proof, the adoption and adherence to recognized standards of care (SOCs) provide protection. There are a number of ethical and professional reasons for implementing a formal SOC program; but from a litigation standpoint, adherence to SOCs is an affirmative defense meaning the plaintiff must attack the SOC (as opposed to the utility s actions), and failure to follow a recognized SOC is quite negative it implies the possibility of negligence. Standards of care are crucial in any litigation, and at a minimum a recognized SOC must incorporate three different elements (Reiber, 2009):

110 Answers to Challenging Infrastructure Management Questions 1. It defines a specific duty (or duties) that are to be performed by the utility. In effect, the SOC recognizes a responsibility on the part of the utility to its customers, and prescribes a minimum set of actions required in response to certain (well-defined) events. 2. It should be codified by a governing, and/or standards body. SOCs are not what any single utility claims them to be, they must be recognized by the broader industry. 3. It must be widely disseminated and readily available to all the member utilities. It is not enough to be effective at resolving consumer issues. Utilities must be perceived as being proactive in the face of a problem, and have documentation to prove it. The AWWA s G200 Series of SOCs captures our evolving understating of water chemistry, hydraulics and materials science, and translates that into practical guidelines that serve both the public and the legal status of the industry (AWWA, 2009). Adoption of an SOC is an affirmative step that recognizes the most powerful weapon of the plaintiff s attorney is indifference on part of the defendant. HOW WELL DO PLUMBING MATERIALS PERFORM? All plumbing and fixtures degrade in service. It is axiomatic that metals corrode, and all waters are corrosive. There are no exceptions, only questions of degree. Even plastic materials degrade due to oxidation and stress related cracking. Black iron, mild steel, lead, galvanized steel, copper, copper alloys and stainless steel, are all examples of common plumbing materials (still in use today) where each material presents distinctly different corrosion morphology, as well as distinctly different forms of corrosion-related failure. Copper remains the most popular plumbing material in North America, yet the oldest domestic copper plumbing systems generally date no earlier than the 1950s. Copper is susceptible to several different forms of corrosion, including intense localized forms of pitting that can cause penetration and failure within a period of months. In some areas of the country, leakage due to copper pitting prevalence is estimated at over 2 percent in the respective housing stocks (Scardina, et al., 2008). In short, there is no immunity to corrosion or degradation, and each plumbing type is different in terms of mechanical strength, durability, and cost of installation. While every plumbing systems has its weaknesses, it is important to emphasize that, overall, the quality of plumbing systems continues to increase, while the inflation-adjusted cost of installed systems diminishes. WHAT S A REASONABLE SERVICE LIFE FOR DISTRIBUTION AND DOMESTIC PLUMBING? Although there is no confirmed standard, the industry consensus is that distribution systems (mains and appurtenances) should provide a minimum useful life in the range of 50 to 100 years. This expectation largely comes from the success achieved with thick wall cast iron pipe installed in the early 20 th Century. (CNRC, 2007). The issue of service life for domestic plumbing fixtures is a more contentious (and litigated) issue. Some manufacturers provide warranties for domestic plumbing fittings of up to 15 years, but rarely beyond. In some cases the

Chapter 4 Water Quality and Internal Corrosion 111 warranty is conditioned or limited to use of the fixture in a water that is considered nonaggressive, even though that terminology is rarely quantified (CDA, 2012). The general industry consensus is that domestic plumbing fittings should provide a useful life in the range of 25 to 35 years. CAN DEZINCIFICATION OF BRASSES BE CONTROLLED THROUGH CORROSION CONTROL EFFORTS? Because of ongoing litigation, yellow brass (a high-zinc copper alloy) has received much recent scrutiny. Yellow brass has been used for decades, and is generally accepted as a highly corrosion-resistant material. Because of its superior machinability, almost all drinking water distribution and plumbing systems use precision components (small valves and fittings) made from yellow brass. Dezincification is a common form of corrosion for yellow brass, and all brasses dezincify to a degree. The fact that a plumbing fitting dezincifies is not evidence of defect, and a moderate degree of dezincification, by itself, is not failure. Dezincification is understood to be a complex process, and there remains fundamental disagreements on how it is both initiated and propagated. The study of dezincification is an active research area. Failures due to dezincification are rare, generally involving either leakage due to structural weakness, or occlusion due to corrosion scales. Structural failure, and/or leakage, occurs through substantial metal loss, wall perforation, and/or wall cracking. Occlusion failure occurs to the extent that a fitting accumulates a dezincification meringue deposit (zinc carbonate scale), resulting in substantially impaired flow through the fitting. The chemical factors influencing dezincification rates on yellow brass components exposed to drinking water are generally thought to include ph, chloride, temperature and alkalinity. Of these, the most important is likely chloride. This is because the chloride ion has a high degree of ionic mobility; and secondly, it is an effective depolarizing agent (electrochemically-polarized metal surfaces corrode more slowly). Chloride is a corrosive agent for copper, and all its alloys. Like all forms of corrosion, dezincification can be controlled by the passivation of the underlying metal. While it is not clear which water chemistry factors are most important at inhibiting the different stages of the dezincification process, simple phosphate-based inhibitors appear to offer a passivation benefit that also limits meringue accumulation (Zhang, et al., 2009; AWWA, 2011). WHAT ARE THE CHALLENGES OF INTEGRATING (BLENDING) NEW WATER SUPPLIES INTO OLD SYSTEMS? Many communities are seeking new sources of water, in large part because of population growth, and in some cases because of groundwater recedence. As utilities expand, they are sometimes called upon to incorporate neighboring utilities into their distribution grid, often blending smaller groundwater supplies into larger surface water systems. Sometimes the merger of systems can change the water chemistry landscape for both distribution systems. Integrating new and different water sources into an existing distribution system can cause disruption of existing pipe scales and corrosion tubercles. This frequently results in colored water events, and in the worse cases generates unpleasant tastes and odors followed by an abundance of customer complaints. The reason for the disruption may be a relatively minor change in the

112 Answers to Challenging Infrastructure Management Questions chemical characteristics of the distributed water, or possible changes in velocity and/or direction of flow. All, or any, of these may disrupt the equilibrium existing between the historic water chemistry and the corrosion scales on water mains across the distribution grid. The process of achieving a new equilibrium between corrosion surfaces and changing water quality is referred to as re-equilibration. The water industry has had some painful experiences with re-equilibration: the Tucson red water episodes, and the District of Columbia Lead Crisis being the most publicized. Although each situation is unique, several factors are important in re-equilibration management, including: Maintaining consistent distribution system water quality, especially alkalinity and ph Minimizing changes in flow velocities and patterns Minimizing stagnant water and high water age Maintaining alkalinity (buffer capacity) above 50 ppm as CaCO3 Low mineral content water is a particular re-equilibration issue because iron release from existing corrosion scales is highly sensitive to variations in mineral content levels (especially chloride). Re-equilibration issues are eminently manageable when addressed before the water quality or flow regimens are changed. Managing re-equilibration need not be a complex exercise in water chemistry modeling. More often than not, it can be as simple as recognizing the need for ph stability, adequate buffer capacity and the occasional use of a corrosion inhibitor. Appropriately understood, re-equilibration control is a proactive exercise in simple water quality maintenance. HOW DOES RE-EQUILIBRATION RELATE TO CORROSION? All metal plumbing systems corrode, and in so doing, form a protective corrosion layer that limits further corrosion. Much of the corrosion control efforts within a water utility are directed at maintaining the stability and protective qualities of these existing corrosion layers. In spite of this, there is always a concern that a change in the character or quality of distributed water may produce unexpected consequences relative to release of corrosion products from distribution system mains or building plumbing. Under some circumstances this involves solubilization of existing mineral scales, and may include a change in oxidation state for some of the metal scale constituents. In severe cases, re-equilibration can weaken the stability of the scale making it more susceptible to hydraulic scour, flow reversals, and water hammer. Scale instability, leads to: Particulate (turbidity) release Red/brown water episodes Higher coliform / HPC counts Increased corrosion. While re-equilibration is most frequently associated with iron surfaces, pitting of copper tubing, accelerated lead release from brass and solder surfaces, and mobilization of manganic sediments are examples of other forms of re-equilibration.

Chapter 4 Water Quality and Internal Corrosion 113 WHAT PARTS OF THE DISTRIBUTION SYSTEM ARE AT GREATEST RISK OF RE- EQUILIBRATION ISSUES? Generally, the areas within a community most at risk for re-equilibration problems are areas likely to have the greatest accumulation of corrosion scales. Areas served by unlined steel or cast iron distribution mains are at high risk, as may be older high-rise buildings plumbed with galvanized steel or cast iron pipe. Of particular concern are households plumbed with old galvanized steel pipes, which in most cases have long since lost their layer of protective zinc, and are now really nothing more than unlined mild steel pipes oftentimes, with a substantial accumulation of corrosion scale. Because of the proximity of this mass of corrosion scale to the consumer, any re-equilibration event in the household plumbing is likely to be severe in terms of its visibility and nuisance value. WHAT ABOUT DESALINATED WATER AND RE-EQUILIBRATION? Desalinated water represents a particular re-equilibration issue, especially water treated by reverse osmosis (RO). Desal water is not free of mineral content, and frequently has total dissolved solids (TDS) levels exceeding 500 mg/l. Moreover, the mineral constituents of RO water are unlike most surface or groundwater sources, and may be exceptionally high in chlorides. Iron release from existing corrosion scales is highly sensitive to variations in chloride levels. Managing the large scale introduction of desalinated seawater into older distribution systems is a serious re-equilibration challenge. HOW DO ISSUES OF WATER AGE AFFECT WATER QUALITY? In terms of maintaining distributed water quality, chemical stability is the goal variability the enemy. The issue of an acceptable water age is different for every system, and largely depends on the nature and layout of the distribution system, piping materials (lined versus unlined cast iron, PVC, ductile iron) and physical factors such as water temperature, disinfectant residual and organic content of the water. Water quality is a perishable product; unlike wine, it never improves with age. What drives the chemical changes associated with water age are internal reactions within the water itself, and reaction between the water and pipe wall (see re-equilibration discussed above). It is important to remember that corrosion scales are inherently unstable, adsorptive, multi-layered structures, often with a porous and protected core populated by a multitude of heterotrophic microorganisms (Friedman, et al., 2010). Any water age that results in substantial depletion of chlorine residual not only allows for coliform regrowth, but creates a chemical reducing environment that facilitates scale dissolution. Destabilized scales place a substantial accumulation of trace metals and biologic mass at the customer s taps (see discussion on dirty water events). Disinfection byproducts (DBPs) can also be a serious water age issue. Although in most finished water the majority of the DBP formation potential is expressed within 24 hours, in some waters, expression of formation potential continues for weeks especially waters containing meaningful bromide concentrations (Walker, et al., 2012).

114 Answers to Challenging Infrastructure Management Questions PERCEPTION VERSUS REALITY: IS THE NATION S DRINKING WATER QUALITY DEGRADING? Much of the talk about diminished water quality is simply not true. The quality of source water and delivered water in the US is not diminishing. If anything, over the past 40 years it has improved, and substantially so. The Water Pollution Control Act (PL 92-500, 1972) is probably history s greatest single environmental success story. Improved water quality in the Great Lakes, the Columbia River Basin, the Mississippi River Basin and the Colorado River Basin are all evidence of this. But that doesn t mean that source waters are inexhaustible. Those regions that have seen increased population pressure (Florida and Southern California for example) have expanded their source water supplies to include desalinated water (in limited cases) and recycled water for non-consumptive purposes. Drinking water regulations have advanced, and the quality of the nation s drinking water has steadily improved. Moreover, all utilities are now required to optimize their respective finished water qualities for corrosion control. The EPA s corrosion control efforts have been widely successful. In the 1990 s almost a third of major utilities could not meet the Lead and Copper Rule criteria. That number is now less than 2 percent (Brown, et al., 2012). In general, drinking water delivered at the consumer s tap is of higher quality than 20 years ago, and less damaging to residential plumbing systems.

CHAPTER 5 CONDITION ASSESSMENT When making infrastructure reinvestments, there are two potential pitfalls. One is underinvestment allowing infrastructure to deteriorate, increasing risks, incurring excessive repair costs, and placing burdens on future generations. The second is misplaced investment or replacing the wrong facilities, wasting money better spent elsewhere. Of these two mistakes, the second may be worse, because it is uncorrectable. Money that is misspent is lost forever. The key to avoiding both pitfalls is accurate condition knowledge. This should not mean applying the latest technology to every asset in the system. That too is wasteful. Rather it means coupling readily available information with cost-effective field data to provide an evaluation that reasonably reflects the true conditions. These accurate assessments are necessary for sound capital investment decisions. They are also needed to elicit support from regulators, political leaders, and the public. As greater focus has turned to our nation s infrastructure, a wide array of tools and techniques have been developed to generate, manage and analyze, condition-related information. These include both physical and statistical techniques for more accurate and cost-effective evaluations. Condition assessment is used to determine both the health of the overall system and the integrity of individual assets. The objectives of effective condition assessment are: 1. Reduce the number and cost of failures, by identifying high-risk assets and enabling cost-effective, targeted, proactive remedies 2. Extend the lives of assets, by distinguishing those that are merely old from those that are truly impaired (Figure 5.1) 3. Generally reduce uncertainties, enabling confident answers to questions from the public and others. This photo illustrates the potential benefits of condition assessment. Although some graphitization is visible in the 8 o clock position, there appears to be ample metal left. The main had never leaked, but rehabilitation is warranted due to the heavy tuberculation. Will a non-structural lining be adequate? Without a detailed condition assessment, we don t really know. Figure 5.1. Unlined cast-iron main, installed in 1926 and rehabilitated in 2005 Condition assessment does more than evaluate the likelihood of failure. By finding specific locations where pipelines are weak, it enables preemptive repairs and life-extension interventions such as anode attachment. In the case of high-consequence assets, condition assessment can produce savings many times the cost of the assessment, by avoiding emergency response and property damage. Perhaps just as important, utilities can avoid overreacting to a 115

116 Answers to Challenging Infrastructure Management Questions momentary crisis, if they have an accurate understanding of the condition of their assets and the associated risks. HOW SHOULD THE OVERALL HEALTH OF THE SYSTEM BE ASSESSED? Condition assessment is one component of a network assessment, as shown in Figure 5.2. A network assessment addresses not just system reliability, but hydraulics and water quality as well. Figure 5.2. Water distribution network assessment Desk-Top Reliability Studies Before going to the field and deploying condition assessment tools, reliability assessment normally begins with a desk-top study of all relevant available data, including failure data (leaks/breaks), pipe material, age, pressure class, soil data, pressure data (including fluctuations) and diameter. Most of this information is taken from the GIS, although supplemental data gathering may also be warranted. Using statistical methods including regression analysis, and Weibull modeling, relationships between the failure rates of various asset subsets and their various causes are investigated. Statistics are also used to forecast the useful lives of different asset classes. Additionally, these desk-top studies include an assessment of risks posed by the different assets. From these analyses, budgets and priorities for infrastructure program are developed. Chapter 2 describes these methods is greater detail.

Chapter 5 Condition Assessment 117 Figure 5.3 Spatial distribution of AC Pipe failures in the East Bay Municipal Utility District The desk-top analysis also generally includes a spatial analysis (Figure 5.3), which provides indications of likely causes (e.g., fluctuating ground water or unstable subsoils), as well as identifying the problem hot-spots. In the spatial analysis example illustrated here, high failure rates were seen in the hilly parts of the utility system (the areas on the right portion of the figure). This prompted a regression analysis which showed a high correlation between pipe failure rate and ground slope. The regression and spatial analysis supported a supposition that bending from ground movement was a significant contributor to pipe failure. A different cause is likely for the high-failure area on the left side of this figure (analysis is continuing). WHERE SHOULD A DETAILED CONDITION ASSESSMENT BE PERFORMED? For high-consequence assets, deciding to perform condition assessment is relatively easy, if the likelihood of failure is judged to be high. In this case, there are two likely outcomes, both of which produce considerable benefit: Assessment confirms a high likelihood of failure. This is beneficial because it prompts actions to mitigate risks, including spot repairs or asset decommissioning and replacement. Catastrophic failure is thus avoided, money is saved, and everyone s a hero. Assessment reveals a lower likelihood of failure than expected. This is also beneficial, because it redirects concerns and resources to other assets, saving money that might have been wasted in renewing an otherwise good asset. Unfortunately, the erroneous conclusion is often that the assessment was a waste of money. Where the consequences of failure are minor, on the other hand, detailed condition assessment may not be warranted, and a repair-on-failure strategy may be acceptable, as shown in Figures 2.10 and 2.12. Or if the replacement cost of the asset is very low, renewal may simply be programmed based on repair frequency, age, or another parameter.

118 Answers to Challenging Infrastructure Management Questions However, the benefits of a detailed condition assessment can go beyond the asset being analyzed. This is better understood by considering how detailed assessments fit into a general model for asset condition assessment (Figure 5.4). Data gathered through a detailed assessment informs decisions not only about the asset being analyzed, but about other assets, including their likelihood of failure and their life expectancies. A detailed condition assessment is thus warranted whenever the potential overall benefit of the assessment is greater than its cost. This may justify the assessment of selected low-consequence assets. Root-Cause Analysis of Failures Detailed Condition Assessment & Evaluation of Assets Statistical Analysis of Failures Priortizaton Model for Testing & Renewal of Assets Supplemental Data Collection Source: HDR Figure 5.4. Pipeline condition assessment model The components of the condition assessment model shown in Figure 5.4 are described below. While most utilities perform each of these steps in some fashion, it is important to consider how information from each component supports system-wide decision processes. Root-Cause Analysis of Failures For all failures, a record of the failure and its repair should be prepared. This helps in later analysis of statistics, particularly in discerning the cause (e.g., corrosion, third-party) and the mode (e.g., rust hole, longitudinal split). For unusual or high-consequence failures, a detailed engineering investigation is warranted, sometimes including laboratory analysis of the failed components. Such an analysis is called for when the failures are early in the expected life-cycle, unusually costly, repeated, unexplainable, or when litigation may ensue. Many failures are not attributable to common aging processes, but rather stem from material defects, operational conditions (surge), and poor construction practices that are highly localized. Examples of such failure analyses include: Analysis of premature failure of PVC pipes, where substandard material, poor construction practices, or third-party damage may be the cause

Chapter 5 Condition Assessment 119 Analysis of failures of HDPE welds, where poor workmanship or poor design may be the cause Analysis of premature corrosion failures, attributed to poorly designed connections (bi-metallic contact), poor choice of corrosion protection system, or poor construction practices Analysis of failures at joints, attributed to use of calcium chloride accelerator in field applied mortar By failing to investigate these failures at their onset, a utility may lose the opportunity to recover costs from the manufacturer, shop, or contractor who was responsible for the substandard quality. If a possibility exists that the failure or its investigation may lead to litigation, legal counsel should be consulted as soon as possible. Particular attention needs to be paid to how emails and other documents are written, to whom they are addressed, and how they are filed. Statistical Analysis of Failures Statistical studies of the population characteristics and failure data point to assets that are more likely to fail and the factors that may contribute to the failures. Statistical relationships are frequently found between failure rates and pipe size (smaller pipes fail more often), pipe age, and environmental factors (corrosivity and ground slope). Also, particular types of pipes, from particular eras, and from manufacturers are more prone to failures than others. From these analyses, priorities and processes for field condition assessment can be developed that further investigate the causal relationships. Supplemental Data Collection The failure and statistical analyses are expected to point to areas where data gaps exist. Such gaps might include: (1) missing records of historic failures, (2) missing information regarding pipe material, class, coating, and lining, (3) missing environmental information about soils, pipe bedding, water, and groundwater, and (4) missing loading information, including transient pressures. Additionally, transient analyses based on current water system operations may be useful. Supplemental field data frequently includes: leak survey data, soil resistivity, and chemical analysis of soil, water, mortar and concrete. Prioritization Model Individual pipes are selected for more detailed condition assessment by performing a risk analysis using the data from existing records and from the root-cause and supplemental investigations. For a pipe where likelihood of failure is low, a detailed investigation is generally not needed. Likewise, if the consequences of failure are low, a run-to-failure approach may be the most cost-effective, and a detailed investigation is not needed. For large or critical mains, a proactive approach may be warranted. Periodic assessments of these mains are appropriate if their conditions are not known and there is a significant likelihood they might fail. In many systems, there are mains where even one failure is too many. [See Chapter 2 for a more detailed description of risk assessment methods and the factors to be considered.]

120 Answers to Challenging Infrastructure Management Questions Paving and other public works projects may also be drivers for detailed condition assessments. If a pipe is nearing the end of its projected life, and major roadway work is planned, then careful consideration should be given to pipe condition, hydraulic capacity, and possible renewal. Paving and roadway replacement, just like pipeline replacement, have considerable social costs from traffic delays and direct costs associated with the work. Patching a recently repaved roadway due to pipe failures causes considerable irritation with the public, and the cost to repair a new road can be astronomical, as many road agencies won t allow a small, simple patch. Curb-to-curb paving and block-long slurry coatings are often required. Roadway paving can thus change a pipeline s risk profile, increasing the possible negative outcomes. While condition assessment is used to help determine the likelihood of condition-caused failures, other factors affect likelihood and should be considered in assessing risks and setting priorities. These factors include: traffic loading, surge, fatigue cycling and others, as listed in Table 2.2. HOW DO I JUSTIFY THE COST OF CONDITION ASSESSMENT? From an economics perspective, investments in condition assessment are warranted when the benefits are likely to exceed the costs. Possible benefits include: Extensions of asset service lives due to greater confidence in their integrity Reductions in future failures due to replacement or rehabilitation of high-risk assets Lower costs of asset renewal, due to targeted rehabilitation/repair of weak areas In addition to economic benefits, the possible social and environmental benefits should also be considered, including public confidence in the utility. A condition assessment need not be expensive, but a precise, comprehensive inspection could be, depending on how it is performed. Key determinants of cost are whether a shut-down and excavation are needed. Figure 5.5 compares commonly used structural condition assessment methods in terms of precision and coverage. As one might suspect, the more precise and comprehensive the inspection, the greater its cost. By their very nature, the more precise inspections will generate more data to be processed, analyzed and managed, and employ highercost technologies. [These methods are described later in this chapter.] Most water utilities seldom perform a detailed condition assessment of small diameter water mains, under the assumption that the cost of these assessments would be better spent on replacement or rehabilitation of the main. Instead, they rely on desktop studies of available data to determine renewal priorities. A new WaterRF project (No. 4471) is investigating whether detailed condition-assessment data gathered from samples of mains can be used to improve these statistical analyses (as discussed later in this chapter).

Chapter 5 Condition Assessment 121 Degree of Inspection Specific Defects General Conditions External Direct Assessment, using: In-pipe condition assessment: Magnetic flux Remote-field electromagnetic Ultra-sonic Remote-field transformer-coupled Electro-magnetic Magnetic flux leakage Visual exams In-pipe leak detection Coupon sampling In-pipe acoustic velocity wall thickness Other methods, where applicable Statistical Studies, using: Non-invasive methods: Leak/break history External acoustic velocity wall Age thickness measurements Diameter Leak-noise correlation Corrosivity and other soil Other active leak detection properties Pipe-to-soil potential measurements Material class Controlled destructive examination Pressure and other data Conditions Inferred from Conditions Directly Measured Samples Inspection Coverage Figure 5.5. Tradeoffs between degree of inspection and inspection coverage HOW DO I DO A DETAILED CONDITION ASSESSMENT PROJECT? It may be useful to view condition assessment as a five-step process, as shown in Figure 5.6. Project Planning Initial Assessment Field Inspection Engineering Analysis Renewal Planning Source: HDR Figure 5.6. Condition assessment of water mains can be considered a 5-Step Process. Step 1. Project Planning Through the analysis of existing data, the needs for a condition evaluation program are identified and priorities for the program are established. Step 2. Initial Assessment The principles of risk management are used to select pipelines for testing and to proportion effort and dollars appropriately. For example, small diameter pipelines are sampled,

122 Answers to Challenging Infrastructure Management Questions with a focus on those with a propensity to fail. This information is used to infer the condition of the population. The risks of larger, more critical pipelines are individually assessed, and detailed assessments are planned as appropriate. The point of performing these analyses is not academic. The objectives are to save money and reduce risks for the utility and its customers. Assessment techniques are selected based on what information is desired and various project constraints. A wide-range of tools and methodologies exist for directly and indirectly assessing the condition of buried water pipes. The cost, precision, and accuracy of these methods vary considerably, and judgment is required to select the most appropriate technology and interpret results. Among the project constraints to be considered are: How accessible is the pipeline? Will excavations be needed? Can the pipeline be removed from service? Can it be dewatered? Can the flow rate be controlled? What permits will be needed? How will traffic be managed? Does the potential benefit of the assessment justify the cost? Step 3. Field Inspections This step involves executing the test plan which addresses multiple aspects of calibration, shut down planning and modeling, data acquisition and data analysis. It is worth noting that no inspection method or even combination of methods provides 100 percent coverage of the asset. For instance, even the most sophisticated scanning methods do not assess pipe joints very well, where overlapping bells and spigots make portions of the pipe invisible. Step 4. Engineering Analyses This step includes analyses of the data provided during the previous steps and culminates in developing the remaining life prediction for the asset. Common mistakes in interpreting pipeline condition assessment data are: Pipes are three-dimensional. Stresses are transferable from weak areas to stronger ones. The problem is four-dimensional. The condition seen today will be different five or ten years later. Not all deterioration is detectable. Brittle materials (cast iron, PVC, AC) are fatigued by the thousands of loading cycles, but the molecular-level deterioration is virtually impossible to discern. Hoop stress is seldom the failure cause. More pipes fail by bending than by splitting. Yet mechanistic models generally focus on hoop stress because it is well understood and easily calculated, and bending load cases are difficult to define. While considerable research has been devoted to developing and analyzing condition data, there is little guidance for interpreting the results. No AWWA standard can be consulted which divides the pipes neatly into acceptable and unacceptable categories. Because this is not an exact science, judgment is needed to assess the risks associated with various conditions and placing these risks in their proper context.

Chapter 5 Condition Assessment 123 Step 5. Renewal Planning For those assets that are impaired structurally, hydraulically, or from a water quality perspective, rehabilitation and renewal alternatives should be considered (see Chapter 6). Even though the condition assessment indicates considerable reserve strength, rehabilitation may be appropriate as a means of restoring performance, reducing failures, and extending asset life. HOW SHOULD SMALL MAINS BE ASSESSED? The traditional approach for small diameter (low-consequence) mains is to monitor the frequency of corrosion-caused repairs, and then schedule renewal when these failures become too frequent. In Chapter 2, typical trigger points for pipe renewal ( rules of thumb ) were discussed and how they might be derived. In addition to monitoring the frequency of repairs, opportunistic assessments may also be conducted. For instance, when the pipe is exposed for tapping a new service, the exposed portion can be assessed. In doing this, two caveats apply: The assessment should be done in accordance with a procedure that involves an ultrasonic test (UT) evaluation or another suitable method. A simple visual examination can be misleading because corroded iron pipes can look fine, with the damage concealed by graphite left behind. Similarly, visual examinations of asbestos cement pipes can also be deceptive. A spot assessment can also give a false sense of security. A badly corroded portion of pipe may be a few feet away from a section that looks pristine. Leveraging NDE Data for Assessing Small Diameter Pipelines (WaterRF Project #4471) As discussed later in this chapter, several methods exist to find and measure structural defects or pinpoint small leaks. Because the cost of using these tools on small diameter pipes can be relatively expensive, they have not seen significant use on small diameter water mains in the US. The WaterRF recently began a project where in-pipe non-destructive examination tools (e.g., Figure 5.7) will be used to sample the condition of small mains, to help assess the overall health of the system, and determine where problems areas might exist. Data from these assessments will then be used to help guide the participating utilities in their main replacement decisions.

124 Answers to Challenging Infrastructure Management Questions The major drawback for in-pipe NDE of small mains is cost. The inspection tool and technical data processing can be expensive, plus getting the tool into and out of the pipe can be difficult. The inspection tool must be sized to match the pipe, so a large tool is needed for a large pipe. For pipelines 6-inches and smaller, however, the tool can often be inserted and extracted using fire hydrants. Source: Photo courtesy of PICA Corporation Figure 5.7. Remote-field electromagnetic tool used for 6-inch ductile iron pipe assessment The Assess-and-Fix Approach (WaterRF Project #4473) In another current WaterRF project, NDE will be used as part of routine pipe rehabilitation, as a way of determining the optimum rehabilitation method to employ for each main. By tailoring the rehab method to fit the pipe condition, non-structural, semi-structural, and fully structural methods can be employed with confidence. Because the NDE device would be employed after the main has been cleaned, UT, EMT, or other devices which require intimate metal contact may be feasible. The technical challenge with this approach is developing a guideline which will match the rehabilitation method to the condition of the main. In doing so, not just the current condition of the pipe is important, but an estimate of future degradation is needed, so that the rehabilitated pipe will achieve its expected life span. WHAT FIELD ASSESSMENTS ARE RECOMMENDED? After a pipeline has been selected for assessment, various methods may be used, as shown in Table 5.1. The choice of method depends on cost, operational constraints, and site conditions. A desk-top study should precede any field work, including an examination of record drawings, specifications, soil reports, repair records, operations data, and cathodic protection data. The desk-top study is needed to help plan and direct the field work, as well as justify the assessment.

Chapter 5 Condition Assessment 125 Table 5.1. Water Main Aging Processes and Field Assessment Methods Material Aging Processes Common Field Assessment Methods Cast iron Ductile iron Steel Asbestos Cement Polyvinyl Chloride Polyethylene Concrete Cylinder Pipe (prestressed) Concrete Cylinder Pipe (non-prestressed) Internal electrochemical corrosion External corrosion Electrochemical Galvanic Stray current (if electrically continuous) Internal electrochemical corrosion External corrosion Electrochemical Galvanic Stray-current corrosion Soft Water Corrosion High-sulfate corrosion H2S Corrosion Minor defects leading to slow crack growth Substandard material leading to slow crack growth Chemical degradation leading to slow crack growth Poor fusion welds leading to slow crack growth Corrosion of prestressing wires Hydrogen embrittlement of prestressing wires Loss of free lime from concrete linings & coatings External sulfate corrosion External carbonation Soil corrosivity measurements External direct assessment Controlled destructive exam In-pipe non-destructive exam (remote-field electromagnetic) Leak detection CP system assessment Soil corrosivity measurements Pipe-to-soil potentials External direct assessment Controlled destructive exam In-pipe non-destructive exam Remote-field electromagnetic Magnetic flux leakage Leak detection CP system assessment Sample & test phenolphthalein stain test crush test Energy-dispersive spectroscopy exam Penetrometer (in-situ) Acoustic velocity Leak detection Sample & test: Acetone immersion test Flattening test Mechanical property testing Sample for laboratory examination and possible accelerated aging Transformer-coupled remote-field EMT Man-entry internal inspection and sounding Acoustic emission Assessment of soil corrosivity Assessment of water corrosivity Sample & petrographic examination

126 Answers to Challenging Infrastructure Management Questions HOW SHOULD THE STRUCTURAL INTEGRITY OF IRON AND STEEL MAINS BE ASSESSED? Soil Corrosivity Testing By measuring soil corrosivity, the potential for external corrosion is determined. Soil resistivity testing is the easiest method of measuring the corrosion potential of soils in place. The electrical resistance of a soil is inversely proportional to its corrosion potential relative to metal pipe. These electrical resistance tests should preferably be coupled with laboratory tests which look at other parameters that also affect corrosivity. Determining where soil is most corrosive is also important in determining where additional assessment will be most productive, particularly if an external assessment is planned involving expensive excavations. [The methods commonly used for soil corrosivity measurements are described later in this chapter.] Pipe-to-soil Potential Measurements For metal pipelines, particularly those that are electrically continuous, the measurement of the voltage potential between the pipe and the soil provides a direct measurement of corrosion activity. Test stations are often used to facilitate these measurements on a periodic basis. The simplest test station is simply an insulated wire with one end bonded to the pipe and the other end brought to the surface and stored where it can be found by a technician. Figure 5.8 shows a slightly more sophisticated test station. This particular station has two wires bonded to each section of pipe, which facilitates a future cathodic protection upgrade, and a permanently installed reference electrode. This detail also shows an insulating flange, which cathodic protection engineers use to electrically isolate one pipeline section from another. For a more detailed assessment, a close-interval potential survey is performed, where the technician uses a trailing wire connected to the test station. As the insulated wire unwinds from a spool, the technician measures the pipe-to-soil potential at intervals of about 1 meter, using a set of reference electrodes at ground level, positioned directly over the pipeline.

Chapter 5 Condition Assessment 127 Source: HDR Schiff Figure 5.8. Cathodic Protection Test Station External Direct Assessment After soil corrosivity and pipe-to-soil potentials have identified areas where potential problems exist, the next step often to excavate and inspect the pipe from the exterior. As cautioned earlier, this should be done is a systematic way, using ultrasonic testing and other methods, because a simple visual examination can be misleading. Source: Photo and graphics: HDR Figure 5.9. External direct assessment of mortar coated steel water pipeline

128 Answers to Challenging Infrastructure Management Questions Figure 5.9 illustrates the external assessment of a steel pipe at a joint where mortar had been field applied. The specific location of the excavation was chosen through a close-interval potential survey, which indicated a high rate of corrosion at this location. In the picture, construction fencing has been used to establish a grid for spot measurements of the electrical potential. The resulting data (shown graphically) indicated significant corrosion, which was later confirmed by removing the mortar. Additional analysis of the mortar showed high levels of chloride, probably from the use of calcium chloride admixture, which is often used to accelerate the setting of the mortar, but should never be allowed. External Structural Condition Inspection Tools for Iron and Steel Mains The following is a list of non-destructive examination (NDE) tools that can be used for the external inspection of iron or steel water mains. Generally these tools are employed to perform spot assessments. To use these devices, the water main must be exposed, which generally will involve excavation, but the main can often remain in service. Electrical Potential Measurements As shown in the preceding figure, potential measurement can be used to detect anomalies in coatings. A negligible potential difference between the pipe and the probe will indicate inadequate coating (i.e., a holiday ). An unusually large difference may indicate that corrosion under the coating is interrupting the flow of current. Hand-held Ultrasonic Testing (UT) Devices These devices are inexpensive and widely used for determining the thickness of the pipe wall at specific spots. Close contact with the metal surface is required, and generally water is used as a couplant between the material being tested and the device. UT utilizes high frequency sound energy directed through the metal, which is reflected back to the transducer by the external surface. UT testing requires the removal of protective coatings and smoothing (cleaning and grinding) of the pipe surface for intimate contact with the metal. Although UT is generally used to assess the thickness of metal, it can be used for thickness testing of other solid homogeneous materials. Automated Ultrasonic Testing Devices have been developed to provide systematic external UT scanning of pipelines. Guided-wave Ultrasonic This method allows the scanning of up to 100 feet of pipe in both directions, from a single excavation. It is applicable to pipelines that are continuous, such as steel pipelines with welded joints. On heavily coated or lined pipe, the wave attenuation limits its usefulness. The method also cannot detect individual pits or distinguish internal and external corrosion, but can detect localized areas of thinning.

Chapter 5 Condition Assessment 129 Magnetic Flux Leakage (MFL) By detecting areas where magnetic fields leave the pipe wall, Magnetic flux leakage determines where metal loss has occurred. Several companies offer MFL tools that work from outside the pipeline, scanning short segments of pipeline within an excavation. This method requires close, contact with the pipe wall; cement mortar coatings must typically be removed. [See below for a more detailed description of in-pipe MFL tools.] Electromagetic Techniques (EMT) Both remote-field and broadband EMT devices have been adapted for externally scanning short segments of iron and steel pipelines within excavations. Broadband electromagnetic technology works by generating a pulsed induced electrical current that flows in a circular path that propagates through the metal and is detected by a receiving probe adjacent to the exciting probe. The pipe wall thickness is related to the change in the signal over time. [See below for description of in-pipe remote-field EMT tools.] These methods do not require removal of the protective coating or preparation of the steel or iron surface. Electromagnetic Acoustic Transducer (EMAT) This technology uses electromagnetic fields to induce ultrasonic waves within the metal. Unlike UT, a couplant is not required, but the device must still be held close to the metal surface. Integrity Testing using Controlled Destructive Examination of Iron and Steel Mains Controlled destructive examination (CDE) is a quick and inexpensive method used to find large weak areas of pipe those that could produce a large rupture. Unlike the spot assessment techniques just mentioned, this method tests the entire pipeline. The process involves pressure testing sections of pipeline in a tightly controlled manner, so these weak areas can be detected and further assessed. This can be done with no risk of property or other consequential damage. If no weak areas are discovered, the owner is provided assurance that the pipe will perform well for several more years, without a risk of catastrophic breaks. The Los Angeles Department of Water and Power used this method to evaluate over 100 miles of large-diameter riveted and welded steel pipe originally installed between 1890 and 1940. Through these tests, the utility confirmed that the likelihood of catastrophic failures of these pipelines would be minimal over the next several years. This allowed the utility to defer several hundred million dollars of planned replacements. The method entails isolating the main using existing valves, then elevating the pressure using a pump (because valves on most large mains don t close tightly, a large, continuously running pump may be needed.) The pressure is raised in small increments, following an engineer-developed plan, while closely monitoring pressure and flow from the pump. If the pressure suddenly drops and the flow suddenly increases, a leak has been triggered, and the pump is shut off. Various methods (as described later in this chapter) can then be used to find the leak. During the repair of the leak, the condition of the pipe is assessed at a point of known weakness.

130 Answers to Challenging Infrastructure Management Questions Admittedly, this is counter-intuitive who wants to make a pipe leak? But the elevated pressure is not causing the leak; the leak is caused by corrosion or other condition problems. The test is merely triggering a leak that will occur eventually (probably at a much less convenient time). CDE is similar to performing a stress test in a doctor s office to detect heart problems something that could be quite deadly in a less forgiving setting. In-pipe NDE Methods for Iron and Steel Mains Although many smart pigs have been developed for examination of oil and gas pipelines, most require intimate contact with the pipe wall, and cannot be used with mortar-lined or significantly scaled mains. Remote-Field Electromagnetic Technology (RFEMT) RFEMT testing does not require intimate contact with the pipe wall, and is currently available in several platforms, including tethered and non-tethered ( free swimming ) devices propelled by the water. These tools can measure and record defects in miles of pipelines between launching and receiving stations, providing a detailed, full-body scan of the pipe. The method employs a transmitter and receiver spaced several pipe diameters apart (Figure 5.10). Both the transmitter and receiver must be sized relative to the size of the pipe (a 4-inch diameter tool will not work in a 12-inch pipe). By comparing the signals at the receiver, differences in impedance are detected which indicate metal loss in cast iron, ductile iron, and steel pipes. From sophisticated data processing, the size and location of corrosion pits are recorded, as well as general corrosion losses. This method was first identified in a 1992 WaterRF study (Jackson, et al.), where it was described it as remote-field eddy current. Source: PICA Corporation Figure 5.10. Remote-field electromagnetic scanning Although the method works in cement mortar lined or tuberculated pipes, inspection of heavily scaled pipe can cause water discoloration and associated complaints and concerns, as well as concerns that the tool may become stuck. While tools are capable of passing through bends, it is good practice to employ cleaning pigs and proving tools before launching the expensive device, but because the tool emits an electromagnetic signal that penetrates the pipe, its location is readily detectable.

Chapter 5 Condition Assessment 131 Magnetic Flux Leakage (MFL) MFL is currently used for approximately 80 percent of the in-pipe inspections performed by the oil and gas industry. Until recently, magnetic flux leakage (MFL) testing was believed to be one of those techniques that could not be effectively used for mortar lined pipe. However, the San Francisco Public Utilities Commission has funded the development of a tool using stronger magnetic fields and employed it to examine miles of steel pipe on its Hetch Hetchy aqueduct system, with reportedly good results. Whether MFL will be adapted for use on smaller diameter water mains is not certain. MFL use with softer cast-iron is considered technically difficult. Source: Pure Technologies, Inc. Figure 5.11. Schematic illustrating magnetic flux leakage In MFL, strong magnets are held close to the steel surface. As shown in Figure 5.11, the lines of magnetic flux travel linearly through a uniform pipe wall, but if a defect exists, the magnetic flux is distorted and leakage is detected by a sensor. For the testing to be effective, the distance between the magnets and the pipe wall must remain constant. Difficulties can be produced by pipe scale, ring deflection, non-uniform linings, and other problems that bump the magnets or sensors away from the pipe wall. Other Smart Pigs Although smart pigs with arrays of UT devices have been developed and used for oil and gas pipelines, cement mortar lining or tuberculation, as typically found in water pipes, interferes with the intimate contact needed between the UT device and the metal surface. Even a polymer coating can interfere. Broadband EMT, on the other hand, has potential applications as an in-pipe scanning tool for the water industry, since it works well in the presence of cement mortar and other linings. A device similar to Figure 5.12 will soon be trial tested on a 6-inch cast-iron water main as part of Project 4471.

132 Answers to Challenging Infrastructure Management Questions Source: Photo and graphic: Rock Solid Group Figure 5.12. In-pipe broadband EMT device and output HOW SHOULD THE CONDITION OF ASBESTOS CEMENT PIPE BE ASSESSED? The weakening of AC pipe is often somewhat uniform and is thus detectable using sampling techniques. Weakening of AC pipe can occur both internally and externally, from soft water, soft groundwater, or high-sulfate ground water. Assessment of AC pipe typically entails removing coupons or sections of the pipe and performing physical, chemical, and/or microscopic scanning tests. In Chapter 3, Figure 3.6 showed the most common condition assessment test for AC pipe, where phenolphthalein had been used to detect Ca(OH) 2, (free lime). The presence of free lime (high ph) indicates essentially undeteriorated material. However, as shown in the adjacent energy-dispersive spectroscopy graph and as confirmed in various other tests, lack of free lime does not necessarily indicate lack of calcium and inferior strength. At best, the phenolphthalein stain and EDS/SEM methods are very indirect ways of assessing AC pipe condition. Ring crush tests (ASTM C500) are more direct indications of pipe strength, but required full-360-degree sections of pipe. The acoustic velocity method (described later in this chapter) promises to provide an easier, more direct, and more comprehensive measurement of remaining AC pipe strength. The use of this test for AC pipe is an area of on-going research (Project 4480, Development of an Effective Asbestos Cement Distribution Pipe Management Strategy for Utilities). HOW CAN THE CONDITION OF POLYVINYL CHLORIDE (PVC) PIPE BE ASSESSED? As described in Chapter 3, the aging of PVC generally entails small cracks that start at small defects, scratches and gouges in the material. Under most circumstances, these defects will be widely and sparsely distributed, leading to only a moderate amount of occasional failures. However, there are cases where defective PVC pipe has been manufactured, leading to premature failures. If an early failure occurs without any apparent cause, substandard material should be suspected. Detecting the defects that lead to PVC failures can be very difficult, but finding poorly made material is less difficult. If poor PVC is suspected, various laboratory tests can be performed on samples taken at the points of failure. If poor material is found, adjacent sticks of

Chapter 5 Condition Assessment 133 pipe should then be assessed, with the investigation expanding, until the extent of poor material is defined. PVC failures have also been attributed to poorly constructed bell-and-spigot joints. One utility indicates that leaks at joints have often caused loss of bedding, resulting in cracked bells due to over deflection. This type of damage might be preventable through an active leak detection program. Other cracked bells have been attributed to over-stabbed joints, which might be detectable through closed-circuit video, but a proof-of-concept test is needed to verify this. In at least one case, the over-stabbed joints were found to arise not from over aggressive construction efforts but from slow downhill movement of the soil. HOW CAN THE CONDITION OF HDPE BE ASSESSED? Most failures of HDPE mains have been attributed to third-party dig-ins or poor quality fusion welds. Because the material is soft, dig-in damage is often instantly detectable (the pipe fails), although latent shallow damage may take many years to manifest. Detecting such damage is considered technically difficult and not generally worth the effort. Poor fusion welds, on the other hand, can be problematic because an undetected systematic error in the welding process could produce multiple failures several years after construction. 68 These errors are generally prevented by employing welding procedures that have been proven and certified in advance, and closely monitoring the weld procedures (temperature, pressure, and time intervals), with the help of data loggers on the fusion machines. Time-of-flight diffraction is a specialized UT method that has been used to detect defective HDPE welds, but an excavation is needed at each joint, for an external direct assessment. Chapter 3 also discusses the chemical degradation of HDPE when exposed to chlorine. As discussed by Chung, Conrad, and Oliphant (2010), this degradation is detectable through laboratory examination and testing, including an accelerated aging test (ASTM F2263). ISN T THERE AN INEXPENSIVE, NON-INVASIVE METHOD FOR SMALL MAINS? Described below is a promising, emerging method, but the convenience and economy it provides comes at the cost of precision and resolution. Acoustic Velocity Testing The speed at which sound travels along a pipeline depends upon the stiffness of the material. By measuring differences in sound speeds at various points along a pipeline, general corrosion losses can be detected using external leak-noise correlators. Equation 5.1 shows the relationship between the speed of sound and the thickness of pipe walls. 69 68 Typical weld inspection entails a visual examination to confirm that a double bead exists all around the outside of the pipe (and the inside of the pipe too, if feasible). However, there are several mechanisms whereby an acceptable-appearing double bead is produces, yet the two pipe segments are only partially fused. 69 Equation and variables provided by Echologics Division of Mueller Company.

134 Answers to Challenging Infrastructure Management Questions (5.1) where, v = measured speed, v o = speed in an infinite body of water D i = pipe internal diameter, K l : bulk modulus of the liquid E = elastic modulus of the pipe wall, t r = residual thickness of the pipe (Source: Echologics Division of Muellar Company) Because these tests are generally performed using available and accessible appurtenances such as hydrants and valves (Figure 5.13), the testing proceeds quickly and the cost is relatively low. When performed in this manner, the testing is also non-invasive and does not impact operations. The major limitation is that only the average thickness between the two detection points is calculated. This method cannot detect localized corrosion where the loss of material is insignificant overall. Corrosion pits in particular will not be detected, unless the pitting is widespread and represents a significant loss of metal. This could produce a false sense of security. While pipelines that test as bad are likely impaired, pipelines that test as good could still fail. On the other hand, if the method is accurate and a good pipeline subsequently fails, the failure should be repairable since such a pipeline would not be suffering from widespread weakening. This method should be particularly attractive for pipelines where general degradation is believed to be present from internal corrosion or burial in uniformly corrosive environments. A particular promising application is measuring the soft-water internal degradation of AC pipe. Source: HDR Figure 5.13. Acoustic thickness and leak testing using noise correlators at LADWP

Chapter 5 Condition Assessment 135 In a research project conducted for the US EPA, two in-pipe leak detection tools 70 were also used for calculating wall thicknesses in a similar manner as just described. By measuring variations in the speed of sound at several locations, theses in-pipe leak detectors should be able (at least in theory) to detect more localized corrosion and more specifically define the extent of degradation. While the results of the EPA study indicated that more research was needed, the method showed great promise. One problem with the EPA test was that the generally good condition of the pipe and its small range of anomalies did not permit a thorough evaluation. 71 The technology company behind these in-pipe leak detection tools is continuing to develop this method for assessing the condition of 12-inch mains and larger. HOW CAN I DETERMINE THE CONDITION OF A PRESTRESSED CONCRETE PIPE? Not all prestressed pipes are equal. As discussed in Chapter 3, the likelihood of PCCP failure is greatly affected by where and when a pipe was made. One manufacturer in particular was responsible for a disproportionately large number of failures, and pipes made between 1971 and 1979 are especially troublesome. Fully 50 percent of the catastrophic leaks and breaks recorded were on pipes manufactured during that period, and a large portion came from the one manufacturer. Thus, the first step in evaluating PCCP is to determine how vulnerable is the subject pipe, based on its date and place of birth. Particularly is shop drawings and specifications are available, a utility can make a preliminary estimate of risk, and determine the appropriate course of action, without spending much money (Romer et., al. 2008). A recent publication, Best Practices Manual for Prestressed Concrete Pipe Condition Assessment: What Works? What Doesn t? What s Next? (Zarghamee et al., 2012) provides methods for prioritizing PCCP for condition assessment, describes available condition assessment and monitoring technologies, and provides guidance for determining failure safety margins and service life prediction. The manual discusses benefits and limitations of the existing technologies, gaps in knowledge, what works and what doesn t in management of pipeline assets; and what further research and field work are needed to improve PCCP condition assessment and pipeline asset management. Remote-Field Transformer-Coupled (RFTC) RFTC is a technique that is effective in finding broken prestressing wires. Through the use of an electromagnetic field, an electric current is induced in the helically wound prestressing wires. The induced current is detectable by a receiver some distance away. If the wires are broken, the current is interrupted. By measuring changes in the detected electric field, the numbers of broken wires can be estimated, and the degree of structural impairment can be calculated. Although this technique has helped many utilities find and fix distressed sections of pipe, broken wires near the joints cannot be detected, since the induced electrical current cannot pass from one pipe stick to the next. These blind areas represent approximately 10 percent of most 70 These in-pipe leak detection tools are described later in this chapter. 71 The study evaluated acoustic velocity pipe wall thickness assessments using both a non-invasive leak-noise correlator and two in-pipe leak detection tools. While results have not been published, they have been presented in several industry forums. See Nestleroth et al. (2012) for a related study of leak detection technologies.

136 Answers to Challenging Infrastructure Management Questions pipelines. Several studies, including Project 2608 External Corrosion and Corrosion Control of Buried Water Mains (Romer and Bell, 2005), have examined the effectiveness of this method. While limitations and inconsistent results were found, the method is considered largely effective. Acoustic Emission Monitoring Acoustic emission monitoring, as described later in this chapter, is used to listen for the sound of breaking prestressing wires. When such a sound is detected, the location of the wire break can be calculated by comparing the signals from detectors on both sides of the break. Manned In-Pipe Inspection and Sounding Although this technique is old and low-tech, it can still be very efficient and effective. Visual inspections detect interior cracking that can be indicative of distress. Sounding refers to tapping on the interior mortar. If a hollow sound results, the prestressing force may be gone. Breakage of prestressing wires causes the pipe to expand radially, resulting in detachment of the lining from the cylinder. Seismic Pulse Echo This technology uses impact from a metal sphere to generate ultrasonic compression, shear, and surface waves to assess the condition of PCCP. It can be used internally or externally, but inspection over long distances is time consuming. WHAT TECHNIQUES CAN BE USED ON NON-PRESTRESSED CONCRETE PIPE? While many of the in-pipe NDE methods previously described have promise, none has been demonstrated to work well in consistently assessing the condition of non-prestressed concrete pipes, for the reasons described below: The highly irregular composition of the pipe creates noising images, making it difficult to discern all but the largest of defects. Although the breakage of several reinforcing bars might be detectable to RFTC methods (particularly for helically wrapped steel), an advanced state of deterioration would already exist before anything is detected. Similar limitations exist for acoustic velocity testing. The pipeline would likely be in a state of failure before significant differences in mechanical stiffness would be discernable. This is not to say that these methods should not be attempted, but a better use of resources may be a more traditional approach of using available data to discern where the conditions are likely to be worst, then excavating the pipe for an external direct assessment. Internal visual inspections may also be considered, particularly if manned entry is feasible. Manned entry is preferred for being able to detect and investigate cracks and other damage more readily than CCTV, however the logistics and safety procedures take considerably more effort.

Chapter 5 Condition Assessment 137 HOW DO I ASSESS A LARGE-DIAMETER PIPE THAT CANNOT BE TAKEN OUT OF SERVICE? For larger diameter pipelines, the economic benefits of performing condition assessment are generally compelling. For a tiny fraction of the pipeline s value, a detailed assessment will produce data needed to assess its future serviceability, estimate the risks of its failure, and determine rehabilitation options. Most importantly, catastrophic failures can often be prevented by fixing proactively the weak areas identified through condition assessment. The difficulty with assessing these larger pipelines is not usually a business justification, but rather a logistical one; how can the pipeline be accessed for an effective assessment? Larger pipelines are often critical facilities where shut-downs for tool insertion/extraction are difficult. Moreover, access to these pipelines often entails large, deep excavations, in heavily-travelled streets. Where direct assessments of large pipelines are not feasible, their conditions are often inferred from various indirect assessment techniques, as previously described. The traditional approach starts with a desk-top review of the design and shop drawings, followed by an assessment of soil corrosivity involving measurements of pipe-to-soil potentials, soil resistivity, current mapping, and laboratory testing of soils. External direct assessments may then be conducted, preferably where the likelihood of deterioration is highest. The limitations of these methods are obvious; the data are either very indirect or very limited. Supplemental information might be provided by assessing the condition of smaller nearby pipelines of similar construction, then using this information to help deduce the general condition of the larger pipeline. Ultimately, if you cannot effectively assess the condition of a pipe, and the pipe is crucial to system operations, and you have reasons to believe the pipe may fail, perhaps you should construct a second pipe. The second pipe provides the redundancy needed to allow proper assessment and maintenance to occur on both pipes. WHY AREN'T THESE NDE DEVICES MORE COMMONLY USED? There are several reasons non-destructive testing of water mains is not more common: The costs of tests can be relatively expensive. Utilities often would rather spend money renewing infrastructure than testing it. Renewal costs can be capitalized. Testing costs often cannot. The logistics of testing can be difficult, with concerns about getting tools into and out of pipes, without jeopardy to system operations and water quality. 72 There are no standards for how results are interpreted. At what point is a pitted pipe unsuitable for continued service? This leaves managers and consultants at risk that second guessing will occur, if something goes wrong. A major impediment to use of these devices is lack of funding for the condition assessment work. Many utility financial departments consider condition assessment an operations and maintenance (O&M) type of expenditure, and O&M funds are typically very limited. Regardless of how categorized, funding for such work is often limited. Making more money available for this type of work would be one obvious response, but such additional money might result in increased water rates, and there is often intense resistance to this. 72 Concerns about disinfection are obvious, but in-pipe tools can also disturb tuberculation, resulting in water discoloration and related issues.

138 Answers to Challenging Infrastructure Management Questions In some studies of customer preferences and willingness to pay, customers have said they would not mind paying more for water, if the money increases system reliability. Also, some utilities have successfully capitalized condition assessment work by relating it to the renewal and rehabilitation work that follows. This allows money for condition assessment to be drawn from bonds and other long-term financial resources. Regrettably, it almost seems a requirement that a utility must have one or more hugely consequential break, before funding for condition assessment and renewal becomes a priority. Without these events, it seems difficult to make a compelling case for condition assessment. Project 2871, Workshop on Condition Assessment Inspection Devices for Water Transmission Mains (Lillie, et al., 2004) includes interviews with utilities to determine why condition assessment tools are not more commonly used. This report argues that business cases for condition assessment can be justified by either deferral or reduction in capital expenditures, and a reduction in operating expenditures. Project 3048, Condition Assessment Strategies and Protocols for Water and Wastewater Assets (Urquhart and Burn, 2008) provided information on (1) the broad range of available asset condition assessment tools and techniques, and (2) guidance on how to effectively use the identified tools and techniques to improve both long-term planning and day-to-day management of assets. City of Calgary Case Study Using NDE to Guide a Small Main Renewal Program For 15 years, the City of Calgary has used data from in-pipe, electromagnetic scans to help select water mains for replacement and rehabilitation. Calgary credits this program of assessment and rehabilitation with a 50 percent reduction in the number of annual break repairs. The savings in repair costs are more than twice the cost of the inspection and rehabilitation program. Calgary got an early start in water main NDE assessment, as one of the proving grounds for a nearby pipeline testing firm. Tests on above-ground (bone-yard) pipes and exhumations of pipes scanned in place soon convinced Calgary Waterworks managers of the accuracy of the technique. With a quickly accelerating break rate and high replacement and repair costs (mains are very deep in Calgary), the City was eager to explore innovative ways of extending the lives of the mains and reducing the costs of repair. Each year, Calgary scans a small portion of its system, using the remote-field electromagnetic method. Several criteria are used to select mains for scanning, including the corrosivity of the soil, the history of leaks and breaks, and whether a scanning tool can be readily deployed. Ideally the scanned pipes will exhibit a moderate amount of corrosion. If there s little pitting, the inspection money is largely wasted. If there s too much pitting, the scanning process itself may trigger a break. The number of bends in a pipe also is a factor. The City avoids passing a tethered tool through more than three 90-degree bends, so that it can be readily retrieved if it gets stuck. As of 2013, 280 inspection runs had been completed comprising 71 miles of cast-iron and ductile-iron mains. Roughly 8 percent of all metallic mains have been scanned, with another sixteen runs planned for 2013 (six miles). Figure 5.14 shows the mains that have been scanned and their badness scores. Badness is a parameter developed by Calgary, and is computed based on the number and severity of pits and reflects the City s judgment regarding the likelihood of main failure

Chapter 5 Condition Assessment 139 While the cost of scanning a pipe in Calgary is less than a tenth the cost of replacement, it only has payback for some mains. The tool has proven most useful for mains where only a few breaks have occurred. These mains are considered candidates for anode retrofit. If the scanning reveals dozens of ready-to-pop through-holes, anode retrofit plans can be abandoned, and the main will be put on the replacement list. On the other hand, if the scanning shows only minor pitting, anode retrofit can be scheduled for a decade later. Additionally, from the results of just a few inspections the conditions of other mains in an area are deduced. In addition to the NDE assessments, Calgary applies data from more than 100,000 soil resistivity readings to infer the condition of pipes below the ground. The anode retrofit program has brought down the number of main breaks in Calgary from 600 to 300 per year, over the last fifteen years, producing an annual savings of $7.5 million. This has paid for the inspection and retrofit program, twice over. Over 15 years, the City of Calgary has scanned about 8 percent of the metallic mains in its system. The NDE data are used to compute a badness score, an indicator of the relative likelihood of pipe failure. The score is based on the number and depths of pits discovered during testing. Calgary uses these scores, along with main break and soil resistivity data to help determine which mains are candidates for cathodic protection retrofits and which should be scheduled for replacement. Figure 5.14. Map showing water mains scanned in the City of Calgary

140 Answers to Challenging Infrastructure Management Questions WHAT DOES A DETAILED CONDITION ASSESSMENT OF A PIPELINE COST? Although precise cost information is desirable, only general answers are currently available. Most projects have their own special requirements, making it difficult to develop reliable unit costs and develop apples-to-apples comparisons. The following factors influence the cost of an assessment, and should be considered when planning a project: Project size. There are many economies of scale. The average cost for doing several thousand feet of main is much lower than for several hundred feet. This is particularly true where the assessment crew must mobilize from an out-of-state location, and the utility is unfamiliar with the testing procedures. Pipe access. If the pipeline can be accessed through hydrants and other available appurtenances, the cost is much lower than if entry and retrieval ports must be constructed. Assessing 6-inch mains using fire hydrant laterals will generally be easier than assessing a 12-inch main using a newly-constructed port. Number of access points. Pipelines with few bends, tees, and elbows are easily assessed using just a few access points. Under ideal circumstances, in-pipe tools can travel miles from entry to retrieval points. Pipe size. Inserting and extracting a tool and most other activities is simply more difficult and more expensive in a large pipe compared to a small one. Excavations are more difficult. Large mains are often located in busy streets, compounding the issues. [However, the benefits of assessing the condition of a large pipe can be huge.] Site-specific issues. As with other projects, the various requirements of each unique site and jurisdiction are important. Traffic control, paving, weather, groundwater, permit requirements and many other factors can greatly magnify costs. The WATERiD website is a repository of case studies, and other sources of qualitative data regarding condition assessment projects, including bid results, completed costs for projects, specifications, available technology providers, assessment tools, and lessons learned. SHOULD I LOOK FOR LEAKS? By detecting leaks early, before they have manifested, several benefits can be achieved. Not only is water saved, but the risk of main breakage is also diminished. Leaking water has the potential to cause loss of soil fines, leading to bending of the pipe and breakage in fact this has been found to be a major cause of pipeline breaks (Makar, et al., 2005). Small sustained leaks may also lead to accelerated corrosion near the leak point and the potential for a break. By finding and repairing a leak, a utility unearths the pipeline at one of its weakest points, where assessment of the pipe condition will be most fruitful. It is much less productive to simply dig up the pipeline at a random spot, where corrosion may be less advanced (Ellison, et al., 2001). Leak detection programs are recommended for pipes of all sizes for the following reasons: Leak detection can be performed relatively inexpensively

Chapter 5 Condition Assessment 141 Small leaks can eventually become big leaks. It is better to fix them when they are small: less water is lost, there s a much lower risk of property damage, and the repair work can be scheduled at a convenient time. Leaks often occur where the pipe is rapidly corroding. The repair location can be an optimum spot for an external assessment. Leak rate audits and monitoring can gauge the value of lost water. Also, by trending leak audit results, the system s health can be monitored. HOW DO I FIND LEAKS? Water Loss Audits and Leakage Analysis Water loss audits are often the first step in any leak management program. Water loss audits tell a manager, first of all, whether significant problems exist. Secondly, if water loss is high, the audit often indicates where to look. Standard practices in this area have been evolving rapidly. The key recent references for water loss control programs and water audits are authored by the AWWA Water Loss Control Committee (WLCC) and are Manual M36: Water Audits and Loss Control Programs, 3 rd Edition, 2009, the AWWA Web page called Water Loss Control Resource Community, and a June 2013 Journal AWWA article by Chastain-Howley et al., Water Loss: The North American Dataset. The Water Research Foundation also anticipates having a new report out in 2014 on component based leakage analysis which could prove helpful in finding leaks. Leak Surveys A leak survey should follow the water audit, to narrow the search further. Traditional leak surveys start with a quick scan of all contact points within the zone, using leak detection equipment. The addresses where leak indications are received are recorded for subsequent investigation. After the initial survey, a second survey is performed at each suspect location, leading to a more detailed investigation, if the indication of a leak persists. Although traditional leak surveys have been performed using aided listening techniques, most leak surveys now employ digital correlators. With correlators, the survey is less subjective (and less prone to human error), the data is digitally stored for future processing, and fewer contact points are needed (Lander, Fendelander, and Francett 1999). Leak Detection Equipment? Digital Correlators? For as long as there s been pressure pipe, people have looked for problems with their ears. For professionals and amateurs alike, the sound of escaping water is often the best indication of a problem. Over the last few decades, various listening aids have been developed, but the ancient sounding bar a simple metal bar held against the ear is still sometimes used. Among the higher tech tools is the leak noise correlator, a computer that analyzes the noises received simultaneously by two or more hydrophones or vibration sensors 73 placed at 73 While the hydrophones are much more sensitive than vibration sensors, they require contact with the water, so can be more difficult to use.

142 Answers to Challenging Infrastructure Management Questions different points along the pipe. By comparing how the sensors receive the noise, the correlator can pinpoint a leak that s in between, often with a high degree of precision. The correlator s success varies with the size of the leak, the size of the pipe, the type of pipe, the distance between the transducers, and interferences from extraneous noise. A correlator is a good tool for finding hard-to-locate leaks, particularly on small-to-medium-diameter metal pipes. On plastic pipes, sound attenuates more quickly, making leaks more difficult to detect, but significant advances in software in the last decade has improved the likelihood of finding PVC leaks. 74 Once a general leak site has been determined, other tools can be employed to find the leak with some precision. Ground mikes can be used over pavement. The mikes are moved around at 5 to 10-foot intervals, until the most audible leak noise is detected. Sometimes this is followed by drilling a small hole through the pavement and inserting a metal rod into the ground coupled to a high-frequency microphone. Several holes may be necessary to pinpoint the leak. In-pipe Leak Detectors The problem of finding leaks on larger, non-metallic pipes led to a technique using a neutrally buoyant hydrophone for listening from within the pipe itself. Using a parachute-like attachment, the hydrophone is carried downstream, up to 2 miles inside a pressurized pipe. The hydrophone drags behind it a communications cable. The parachute is eventually collapsed, and the device is reeled back. Areas where leak noises occur on both passes of the hydrophone are then targeted for further investigation (Makar and Chagnon 1999). A more recent invention is a self-contained ball with on-board detection and recording. The ball is inserted and retrieved from small ports in the pipe, and leaks are located by calculating where the ball was when the leak noise peaked. The ball rolls along the bottom of the pipe, propelled by the flow of water. A certain minimum flow is necessary to assure that the ball travels from start to finish. WHAT ABOUT CONTINUOUS LEAK DETECTION? When the first version of this report was published in 2001, the authors remarked, Perhaps in the future, permanent transducers might be installed throughout the system for continuous data collection and processing, providing early warnings of problems. This future has arrived. Through advances in digital and communication technologies, a widely dispersed data collection system is now possible. Several companies currently offer systems that provide network-wide daily leak detection. Acoustic Sensor Data Loggers Acoustic sensors coupled with data loggers can be installed at various points in a distribution system (such as the top of valve operating nuts within valve cans), recording the sound continuously. These devices collect and transmit information to a receiver for download 74 A study by WaterRF/National Research Council of Canada found that detection equipment was capable of finding leaks on PVC piping, but success was fleeting. Automatic filter settings were set too high and operators tended to shift settings in the wrong direction. Leak noises in plastic pipes are dominated by low frequency components. See Hunaidi, 1998.

Chapter 5 Condition Assessment 143 and analysis. By analyzing and comparing the sounds produced during the night, portions of the system can be prioritized for further leak detection investigations. The City of Las Vegas, one of the first to try this technology, employed the data loggers to find suspected leaking mains and laterals. Data were collected by drive-by receivers, then analyzed in the office. More detailed investigations were then conducted of areas where persistent noise was detected. After collecting data in one neighborhood, the devices were then redeployed to another. Automatic Meter Reader (AMR) Systems By monitoring round-the-clock flows using AMR technology, a utility can flag those customers accounts where persistent consumption points to leakage. Customers can be alerted though reports included in the bills, or through an email or phone call, if leakage is substantial. Although these leaks are on the customer-sides of these smart meters, informing customers or these problems generates good will and helps with conservation efforts. A more advanced application is time-synchronous automatic metering. Because water is incompressible, the sum of flows in and out of any system should balance. Synchronized meters within a DMA can thus alert a utility in real time to significantly sized leaks, potentially providing an early warning of major problems. [The ability of these systems to detect smaller leaks is more limited, given that measurement errors are unavoidable.] Combination Acoustic and AMR Systems By combining automatic meters with acoustic sensors, both acoustic and flow data can be transmitted to the utility using a common communication system. While the automatic meters flag potential leakage on the customer side of the meter, the acoustic devices flag potential leakage on both sides, including leakage on the water main and service lateral. As these distributed automatic systems become more common and data becomes more prevalent, our ability to use this information will increase. WaterRF Project 3183, Continuous System Leak Monitoring-From Start to Repair (Hughes, et al., 2011) pilot tested a system where acoustic monitors were placed throughout a network and continuously monitored through the automatic meter infrastructure system. Through this 3-year study, 172 leaks were detected, using 500 monitors. In addition to simple leak identification, the system providing data on initiation and progression of the leaks, which enabled correlation with weather and other external influences. The study found the system effective in finding leaks and reducing water loss, although in areas where short segments of plastic pipe had been used (for iron pipe repairs), detection was less effective. Other Leak Detection Tools Techniques that are less commonly used in the US, but have seen use in other countries are described below. Each of these techniques has been investigated by the WaterRF and the US EPA. A good overview is found in Thomson and Wang (2009).

144 Answers to Challenging Infrastructure Management Questions Ground Penetrating Radar (GPR) This technology has been adapted to help find leaks by looking for changes in soil density. High clay content soils, due to their greater conductivity, attenuate the GPR signal and significantly reduce the depth of GPR penetration and minimize its effectiveness. Radio Frequency Interferometry Low-power, ultra high frequency radio waves are transmitted into the ground, which reflects from the leaking water back to a receiver. By analyzing the data for frequently changing signals, leaks are distinguished from other data. Testing on water mains in Hong Kong showed the ability to pinpoint leaks within 100 cm at a distance of 30 meters. This technology was determined to be particularly effective where a pipeline passes under a structure, and would not be accessible to other technologies. Infra-Red Thermography Variations in temperatures along a pipeline can indicate areas where leakage is occurring. By using infra-red thermography, a low-flying aircraft can quickly assess a pipeline, particularly through rural, undeveloped areas. HOW DO I LOCATE THE PIPES? It s not unusual for a utility to have an incomplete record of their asset inventory, including little knowledge about where the pipes are. To assemble this information you may want to comb the as-built drawings and other records, as well as interview current and former employees. You might also interview other utilities and utility contractors. A common, very relevant question is where exactly is the main in this street? It s the question you should ask when designing a new pipe and certainly before digging up the street. For this question, records and recollections are seldom enough a field investigation is usually in order. For design purposes, a simple ground surveillance is useful, particularly where it is supported by record drawings. Valve covers, pavement markings, and pavement patches provide evidence of utility locations. The location of all utility appurtenances should be measured and recorded, including valve caps, hydrants, vaults, meter boxes, manhole covers, electrical pull boxes, conduits, and power poles, using high-quality GPS units. Cracking in the pavement will sometimes indicate where the ground has been trenched in the past. Prior to actually digging, a method of physical verification is usually required; the most common method is a pipe locator. Four basic types of locating devices are commonly used: metal detectors, ferromagnetic locators, radio transmission locators, and nonmetallic pipe locators. 75 Their use is relatively simple, but it s important to match the right equipment to the application. Ground penetrating radar is another technique that is somewhat more complicated, but is finding greater and greater application. Pot holing is a traditional method for confirming location, depth and other information, and it too has undergone significant advances in the last few years. An understanding of these methods and tools is useful: 75 Most of the information on pipe locating devices is taken from Von Huber 1999.

Chapter 5 Condition Assessment 145 Metal Detectors Metal detectors work well for finding valve boxes, manhole covers, and other metal objects located relatively close to the surface. A metal detector uses a flat detection coil on the end of a pole. The device will signal the location of any metallic object near the surface, such as scrap metal, coins, or even gum wrappers. Larger objects will produce stronger signals. Ferromagnetic Locators Ferromagnetic locators are simple one-piece wand-type devices which can be used for any objects containing iron, such as steel, cast-iron, or ductile iron pipe. Detection is done by sweeping the device from side to side, holding it at an angle to the ground. The tools work by detecting disturbances in the earth s magnetic field caused by pipes or other metal objects. Because the fields are weak, and these changes are very slight, small metal objects close to the device can disrupt the detection, including steel-toed boots, or even wrist watches. The devices can be greatly disturbed by large metal objects, such as cars, fences, or metal buildings. Without such interferences, they can detect pipe to a depth of approximately 8 feet. Radio Transmission Locators Radio transmission locators are slightly more complicated tools, but produce very reliable results. In most applications they can specifically target the object being sought rather than finding anything that happens to be in the ground. Two units are required, a transmitter and a receiver, and these units are configured in various ways for different applications. For example, the transmitter may be coupled to a hydrant or other appurtenance. Then the receiver can be used to trace the pipe. When a direct connection to the pipe is not possible, or when the distance from the available connection is large, the transmitter can be placed over a known location of the pipe, inducing a signal within the pipe that is then detected by the receiver. When the location of the pipe is unknown and a direct connection is not possible, the transmitter and receiver can be connected together with a handle and the general area scanned. Since radio transmission locators utilize the pipe as an antenna, to be detectable the pipe must be metallic. Non-metallic pipe can be detected if a copper wire or aluminum tape has been buried alongside the pipe, particularly if a direct connection to the conductor can be made. If no tracer wire exists, the pipe can still be located if it is removed from service, an electrician s fish tape or a rod is inserted within the pipe and a signal induced. (Using a plumber s snake is not recommended, unless there is assurance that it has not been previously used within a sewer.) All such items should be cleaned and disinfected prior to insertion within water pipes. Radio transmission locating can also be used to estimate the depth of the pipe, after its horizontal centerline location has been determined. This is done by holding the receiver at a 45- degree angle, just above the ground. The minimum signal will occur at a horizontal distance from the center of the pipeline that is equal to the depth of the pipe. This method works best if the transmitter and receiver are relatively close together, so that a strong signal is available.

146 Answers to Challenging Infrastructure Management Questions Ground Penetrating Radar The use of ground penetrating radar (GPR) has expanded considerably in the last 10 years. Originally developed as a geophysical technique, it can be used to detect buried objects of many types. A key advantage of the tool is that an estimate of the utility depth is obtained. The maximum effective range of GPR varies considerably, from 1 to 30 meters, depending on the type of soil, and the resolution (wave length) that is used. The visibility of objects depends of their size, shape, and the contrast between the object and the surrounding soil. The result of a GPR investigation is fairly abstract image, as shown in Figure 5.15, requiring interpretation by a skilled technician. Other Nonmetallic Pipe Locators Several tools have been developed specifically to locate plastic and other nonmetallic pipes. One method induces an electronic signal within the water which is then detected by a receiver on the surface. Another method uses a special valve to interrupt the flow from a hydrant or service lateral, thereby producing shock waves within the water. The resulting vibrations are detected and amplified by seismic sensors at the ground service. This method works well in close proximity to the exciter. It is particularly useful in tracing service lines. Source: GeoModel, Inc., Leesburg, Virginia Figure 5.15. Ground penetrating radar image Pot holing and vacuum excavation In spite of the high-tech tools, the need for pot holing (exploratory digging) will always exist. Pot holing is often done in advance of detailed design, to precisely locate interferences and determine where connections can be made. It s also required in advance of drilling, boring, or large excavation efforts, to better plan the construction and minimize risks. Pot holing may also be necessary to accurately determine other information such as type, size, or condition of a

Chapter 5 Condition Assessment 147 utility, soil conditions, and bedding materials. The extraction of pipe samples for condition assessment is accomplished with pot holing. For decades, pot holing was performed using combinations of backhoes and hand tools, but with the increased presence of plastic utility lines and direct buried communication cables, even the use of hand tools became a fairly risky endeavor. About 15 years ago, utilities began using vacuum excavation as a safer, and often more efficient method of pot holing. A vacuum excavator is a machine that uses compressed air or high-pressure water to loosen soil, and a vacuum hose to lift and deposit it in a truck. The vacuum excavation concept dates to the 1920s, but advances in equipment design reduced the clogging problems that plagued early equipment. While some utilities have their own vacuum excavation equipment, many more now have contracts for call-out services. Because the ground is not jabbed with sharp metal, there is much less danger that utilities will be damaged. In fact, the method is even used by archeologists as a way of quickly removing soil, without damaging artifacts. Also, vacuum excavation is different than traditional pot holing in that the product is a hole about 12-inches square. Because the hole is small, there is less chance of soil caving or unraveling, and less damage to the pavement. HOW DO I ASSESS SOIL CORROSIVITY? Ideally, this question has already been answered, perhaps during the design of the pipe, so check your files and drawings first. Published maps also provide some guidance look to the U.S. Natural Resources Conservation Service, 76 or the U.S. Geological Survey. Unfortunately, these published maps can also be inaccurate for the purpose at hand. Particularly in urban areas, trenches were often backfilled with a variety of imported or native materials, without regard to their effects on pipe corrosion. This means that corrosion along the length of the pipe may be far from uniform. Perhaps you already know where the hot soils are, where repairs have been common and failed pipe has been replaced. A major factor in determining soil corrosivity is electrical resistivity. The electrical resistivity of a soil is a measure of its resistance to the flow of electrical current. Corrosion of buried metal is an electrochemical process in which the amount of metal lost to corrosion is directly proportional to the flow of electrical current from the metal into the soil. Corrosion currents, following Ohm's Law, are inversely proportional to soil resistivity. Lower electrical resistivities result from higher moisture and chemical contents and indicate more corrosive soil. 76 Formerly the United States Soil Conservation Service.

148 Answers to Challenging Infrastructure Management Questions Source: HDR Figure 5.16. Corrosion engineer performing an electromagnetic survey Electromagnetic Conductivity Survey This procedure uses a radio frequency transmitter and receiver to inductively measure the electrical conductivity of the soil. The technique produces lots of data, relatively economically (Figure 5.16). The soil conductivity can be surveyed to about 20 feet deep at ten foot intervals, which will provide a continuous profile of soil conductivity along the alignment. The conductivity data are useful in identifying the areas for further investigation. Overhead power lines and underground piping can produce erroneous results, so this procedure is usually used in rural areas. Field resistivity tests and soil sampling should then be conducted in areas of high conductivity. In addition, the conductivity data can be used for cathodic protection design. Electrical Resistivity Tests along the Alignment by the Wenner Four-Pin Method This procedure gives the average resistivity from the surface to a depth equal to the pin spacing. Pin spacings of 2.5, 5, 7.5, 10, 15 feet and greater, if necessary, can be used so that variations with depth can be evaluated. The data are used to augment and correlate the conductivity data. Laboratory Tests on Soil Samples Samples are typically tested for as-received resistivity, saturated resistivity, ph, possibly sulfides and oxidation-reduction potential, and analyzed for the chemicals commonly found in soil including chloride and sulfate. Linear Polarization Resistance (LPR) LPR measurements determine general corrosion rates and imbalance (tendency for localized corrosion). These tests require that the entire surface of each of the two electrodes be in intimate contact with the soil or soil extract for the duration of the measurement cycle since

Chapter 5 Condition Assessment 149 the value required for the calculation of corrosion rate is corrosion current density (current divided by the electrode surface area in contact with the corroding environment). Laboratory LPR Tests Lab LPR tests can be performed on soil paste samples and in soil extract solutions. Measurements are performed on a short-term (24 to 48-hour) basis to better emulate steady-state conditions. Field LPR Tests LPR measurements can also be taken in-situ by insertion of probes in freshly exposed soils (usually five minutes in duration). Estimated values for general corrosion rates can be determined, however, corrosion rate information will be skewed toward higher values. Imbalance measurements are generally invalid due to the limited period allowed for measurement. Field in-situ measurements taken near the surface reflect corrosion rates in an oxygen-rich environment and in-situ measurements taken in freshly exposed soils 2 to 3 feet below grade reflect corrosion rates in an oxygen-depleted environment. Stray-Current Evaluation In addition, the likelihood of stray DC electrical current in the soil should also be assessed. This is done by looking for rectifiers and other sources of direct current that might cause stray current corrosion, checking the local Cathodic Protection Committee list for rectifiers in the area, and checking with pipeline owners for cathodic protection systems in the vicinity. CAN I TELL HOW FAST A PIPE IS CORRODING? The rate of corrosion can be measured, as discussed earlier, using pipe-to-soil potential measurements. Because these measurements require contact with the metal and with the soil, they are generally only performed on electrically continuous pipe. Unfortunately, cast-iron, ductile iron, and steel pipe with non-welded joints are generally not electrically continuous, unless special bonding wires have been added across the pipe joint. The only common water main pipes that are electrically continuous by their nature are welded steel and riveted steel, although lead-caulked cast iron mains may also exhibit considerable electrical continuity. Where applicable, pipe-to-soil potential surveys are important methods of assessing the condition of an electrically continuous pipeline. The pipe-to-soil potential should be within a particular range that varies with the pipe material and type of coating. If it is not in the proper range, the cause should be determined. Various reasons are active corrosion, stray current, dissimilar metal corrosion cells, and cathodic protection. To measure pipe-to-soil potentials, electrical contact must be made with the pipeline. Test stations (as described earlier) are frequently installed on pipelines for this purpose, but appurtenances that are electrically connected to the pipeline can also be used, such as air valves, blowoffs, line valves, and hydrants. A second contact must be made with the soil, but this can be done with a temporary reference electrode. The major difficulties with these surveys are:

150 Answers to Challenging Infrastructure Management Questions Contact with soil may involve coring through the pavement. The survey provides information regarding corrosion rates, but cannot determine the extent of corrosion that has already occurred. CAN I TELL IF THE CORROSION PROTECTION SYSTEMS ARE WORKING? Evaluation of Existing Cathodic Protection Systems Cathodic protection systems have been applied to water pipes since the early 1960s. If a line is cathodically protected, pipe-to-soil potential measurements, as just described, indicate the level of protection, and therefore, whether it meets a criterion for full protection. However, before doing a survey, the first thing to check is whether the CP system is even working. Because the anodes corrode and are eventually consumed, testing and periodic maintenance of these systems is required. Fortunately, the maintenance interval is often measured in decades. Unfortunately, this means that maintenance is sometimes overlooked, particularly on smaller systems. Evaluation is done by reviewing maintenance records and checking the condition and electrical output of the rectifiers (impressed current systems only). If a rectifier is cycled on and off, the on and instant-off potentials can be measured. These potentials determine the effect of the CP system on the protected pipeline and if the cycled rectifier is causing stray currents on any adjacent pipelines. In-situ Evaluation of Coating Performance Pipeline current mapping is similar to potential surveying, except that the field generated by the electric current in the pipe is measured, rather than the electric voltage. This means that contact with the soil is not needed. This method has been used very successfully in the oil and gas industries for pinpointing anomalies in the coating. If a good, electrically insulating coating is present, the electric field should remain fairly constant along the length of the pipeline. Distinctive drops in the field strength indicate where the current is being dissipated through small defects in the coating. The method can also be used where cathodic protection is not installed, by employing a temporary power source. In the water industry, this method has been generally unsuccessful in finding problems, primarily because the pipes are not well insulated from the soil or from other pipes. The dissipation of the current is too diffuse to signal specific defects. SHOULD I DIG DOWN TO THE PIPE TO ASSESS ITS CONDITION? Digging up short, randomly selected pipe segments for testing and inspection is usually not a good idea. It may not reveal much and could be misleading. Because corrosion processes are often not uniform, the exposed portion might exhibit little deterioration even when the pipe nearby is about to fail. Moreover, such an inspection can harm the pipe by damaging coatings and introducing oxygen to the bedding material, accelerating corrosion. As discussed earlier, any such investigation should be conducted in locations where the likelihood of detecting deterioration is high, and the inspection should follow a strict protocol so that defects are not overlooked (see External Direct Assessment discussion earlier in this Chapter).

Chapter 5 Condition Assessment 151 On the other hand, if a problem spot has been identified, a detailed investigation is often very much in order. This is an important consideration that utilities often neglect in the ordinary course of work. Generally a defective pipe is first manifested by a leak. Eventually a crew is dispatched, and using clamps, screws, patches, cements and even redwood plugs, they stop the leak. The excavation is then backfilled and they walk away until the next leak beckons them back. The crew generally does not have the time, tools, or training to evaluate the condition of the pipe. Their concerns are getting the water back on, the street back in service, and other leaks fixed. It needs to be recognized that each of these leak repairs is an opportunity. Perhaps, for the first time since it was installed, this section of pipe has been exposed and an assessment of its condition might provide valuable clues to the expected life of the rest of the pipeline. This is not some random segment of pipe, but an area that may be corroding. It may be important to know why. SHOULD I DO COUPON TESTING? Pipe Coupon Removal Removing random pipe coupons or other pipe samples for physical examination and testing is generally not worth the effort. Problems that lead to most pipe failures are normally not uniformly distributed and are more often highly localized. Most coupons thus may show little or no degradation, which could lead to a false conclusion that the pipe is sound, when in fact a failure could be imminent just a few feet from where a coupon was extracted. As with most general rules, there are exceptions one is asbestos-cement pipe. Where AC pipe is subject to internal deterioration from aggressive water, the process can be fairly uniform, and a sampling of coupons can provide information about the integrity of the pipe. When the coupons are taken to a laboratory and coated with phenolphthalein, areas where degradation has occurred will show no change in color, whereas undeteriorated pipe will change to a violet color as it reacts to the phenolphthalein (Benjamin et al. 1996). If significant degradation is noted, other tests, as described earlier in this Chapter should be considered, since the phenolphthalein stain test has several limitations. Coupon sampling may also make sense where remote-field EMT has indicated that a defect exists. In this case, removing and examining the defect may be a way of calibrating the non-destructive measurements, and interpreting other test results. In the UK, cast-iron pipe samples are routinely extracted for detailed examination. The samples are grit-blasted and pits are measured. Then using an analytical method developed by the Water Research Council (WRc), the remaining service life is estimated. This process is essentially mandated by the government s Water Services Regulation Authority (OFWAT), which oversees water utility capital investments and customer services. Based on this analysis, decisions are made whether to line or replace a pipe, and what type of lining (non-structural vs. semi-structural). A final reason to extract samples is when coupons are being cut anyway for service taps. There s no reason not to have these labeled and routinely sent to Engineering for assessment and recordation on the GIS. With enough coupons, the overall degradation of the pipeline can be gauged, and this information is virtually free.

152 Answers to Challenging Infrastructure Management Questions Coupon Insertion Coupons have sometimes been inserted into pipes as a way to estimate the corrosion potential of an environment. This is done by measuring the weight loss of a coupon exposed to that environment. This is a common technique used by corrosion engineers for many different applications. Some water utilities have employed this method, suspending clean, precisely weighed coupons within pipelines and determining metal loss after an extended period. The method is useful for comparing the corrosion potential of different water treatment methods or different metal alloys, using pipe loop studies. However, such a test cannot predict with accuracy the life of a particular type of pipe, since it ignores the exterior environment. Nor should it be used to judge the life of coated metal, since it could not account for differences in coating defect rates between the coupon and the actual pipe. SHOULD I PUT A CAMERA INSIDE THE PIPE? By itself, a camera inside a pressure main provides limited information. It will reveal the extent of tuberculation and maybe the condition of the lining, but it will not discern whether the pipe walls are weak or strong, or whether the pipe is leaking. Closed circuit television observations are also not as simple for water pipe as they are for wastewater pipe. The pipe must often be removed from service and perhaps access openings are needed. Disinfection of the equipment is also a concern. One company has overcome these problems using a push-type video camera that is inserted through fire hydrants (Figure 5.17), while the system is still pressurized. This camera is also coupled with an acoustic sensor, so in-pipe leak detection is simultaneously performed, as the camera travels through the pipe. 77 Source: Photo by Wachs Water Service, Inc. Figure 5.17. Live insertion of combination video/acoustic sensor at fire hydrant While a camera observation will usually reveal little about the pipe integrity, it may be useful in judging the integrity of lining. If the pipe is an important one, information about the 77 Using a similar strategy, fiber optic probes have been used n the Netherlands, inserted through the service pipes, to visually discern the extent of tuberculation (Smulders, 1999).

Chapter 5 Condition Assessment 153 lining may be very important. For a large pipe in particular, detecting and repairing defects in the lining can be very cost effective. Lining observations will also indicate areas where other problems may be occurring, such as distress from corrosion or settlement. If the pipe is large enough (24-inches and larger), first-hand observations by an experienced worker (with a hand-held camera) are more effective than CCTV. When lining defects are found, the larger pipes can usually be repaired by hand. Repairing smaller pipes is more difficult; either the defective section of pipe must be cut out and replaced, or the whole reach between access holes must be relined by a centrifugal lining machine. CAN I MONITOR THE PERFORMANCE OF PIPELINES AND DETECT IMPENDING FAILURES? As previously discussed, acoustic monitoring devices (hydrophones, vibration sensors, data loggers and specialized smart meters) can be installed to provide continuous leak detection. Similar acoustic tools have also been used with considerable success in pinpointing problems in prestressed concrete pipe. Using analytical methods adapted from navy sonar, the faint sounds of breaking prestressing wires can be detected and located. Precise locations are determined by correlating the sounds received over an extended period of time at a pair of sensors. Compared to other PCCP inspection methods, this technique offers the advantage of being relatively low-cost and essentially non-invasive. Hydrophones can be inserted through holes tapped into lateral pipes or into manhole covers set thousands of feet apart. 78 The disadvantage is that this method only detects deterioration that is currently occurring saying nothing about the overall condition of the pipe. In recent years, acoustic emission monitoring has also been accomplished using acoustic fiber optic (AFO) cables laid in the bottom of pipes. The entire cable is an acoustic sensor; wire breaks produce a signal carried by the cable and detected by remote sensors. AFO has helped some utilities detect third party damage to PCCP pipelines (3 cases) in addition to averting PCCP failures from wire corrosion (30 cases). 79 As described in Chapter 6, AFO cables have also been included between the host (casing) pipe and a slip lined (carrier) pipe as a means of detecting and locating leaks. It may be possible to use similar acoustic methods to detect early signs of failure in other pipe materials but this technology is not yet developed. Some evidence indicates that failures of steel and iron pipes may be preceded by small fractures, movements, and leaks. A current WaterRF study, Acoustic Signal Processing for Pipe Condition Assessment (Project 4360) is analyzing the noise detected by these various sensors to see what other information (besides wire breakage) can be discerned. HOW CAN I ASSESS THE CONDITION OF PIPELINE JOINTS? WaterRF published a research study in 2006 on methods to assess joints (Project #2689 by Reed, Smart, and Robinson, Potential Techniques for the Assessment of Joints in Water Distribution Pipelines). While the project did not achieve what it desired to, it included a discussion of joint issues. 78 Tapping directly into the pre-stressed pipe should generally be avoided. 79 Per telephone conversation with John Gallaher, Pure Technologies, Inc., September 5, 2013.

154 Answers to Challenging Infrastructure Management Questions Pipeline joints are often the weakest part of the pipe. As discussed in Chapter 3 and elsewhere: Some rubber gasketed joints are vulnerable to degradation due to chloramine exposure Rubber gasketed joints are also susceptible to hydrocarbon permeation Mortar lined and mortar coated joints are often poorly made, poorly cured, and frequently found to have chloride added, resulting in premature corrosion of the metal underneath Poor joint fusion is one of the leading causes of HDPE pipe failures Many of the NDE methods do not work at or near joints, where bells and spigots overlap and conceal material, or electrical discontinuity occurs and disrupts the test method Small leaks from poorly aligned or poorly constructed push-on joints can lead to erosion corrosion damage to the pipe, or to loss of bedding material, eventually causing breaks The good news is that leaks are often the first sign of joint problems, and an array of methods to detect leaks exists, as described above. BEFORE TESTING A PIPE, WHAT OTHER ISSUES SHOULD BE CONSIDERED? When working on an existing main, the impact on customer service will be a prime concern. Can work be done with a short service outage, or will bypass piping be needed? How will the pipe be kept sanitary? Will you need to disinfect and perform bacteriological testing, before returning the pipe to service? If the unexpected happens, what are the contingency plans? What will you do, for instance, if something gets stuck in the pipe or the pipe (or a valve) breaks? On top of these, there are the usual issues of how to manage traffic, obtain permits, and dispose of water. For pressure testing, a protocol is needed, based on an engineering evaluation of the pipeline. Using record drawings, determine how to isolate the pipeline, what test pressures to apply, and how to apply them. The selection of a test pressure needs to take into account the pipe stresses at the low points and where changes in pressure ratings occur. With careful planning, risks can be reduced, but never completely eliminated. Unfortunately, many managers focus on these risks and decide that condition assessment is too risky. In the opinion of the authors, the risks associated with assessment are often exaggerated, while the potential benefits of assessment are undervalued. As a result, utilities endure higher risks of infrastructure failure. 80 80 In trying to shed blame, utilities often describe these failures as unpredictable, which perhaps once was true, but is a less credible excuse as the use of assessment technology increases.

Chapter 5 Condition Assessment 155 HOW, AND HOW OFTEN, SHOULD I INSPECT MY VALVES AND HYDRANTS? In many older systems, it is not uncommon to find pipelines that are 100 years old, and older, and there s reason to believe that some of these pipelines will continue to function for many additional decades. However, the same cannot be said of valves. There s little reason to believe that any mechanical valve, no matter how rugged, can remain functional indefinitely. Corrosion seizes the gears. Scales, degradation, and erosion destroy the sealing surfaces. Yet, in many systems, there is far less focus on valves than on pipes. Valves are often only replaced, when the pipeline is renewed. A better approach is to consider pipes, valves and hydrants as independent components, with their own life expectancies and maintenance needs. Chapter 3 discussed the need for a regular program of functional testing and exercise to assure that hydrants and valves are maintained in operable condition and to identify malfunctioning equipment. This can be accomplished in conjunction with a unidirectional flushing program. How often this is required is a matter of opinion, but many utilities strive to do this annually. 81 Project 4188, Condition Assessment of Water Main Appurtenances (Marlow and Beale, 2012) provides a practical manual for the condition assessment of appurtenances, including protocols and risk-based approaches to prioritization. HOW DO I EVALUATE TANKS AND RESERVOIRS? Steel Tanks and Structures For steel tanks and similar steel structures, the primary concern is a corrosion evaluation determining if the coatings and cathodic protection systems are working. Inspections should be conducted by trained and certified 82 technicians, experienced in potable water tank evaluations. Where structural damage exists or if a seismic evaluation is required, a structural engineer should also participate. Standard methods of steel tank evaluation include: Visual evaluations. The degree of rusting is graded by applying Society of Protective Coatings (SSPC) Visual Standard for Evaluating Degree of Rusting of Painted Steel Surfaces (SSPC-VIS2) Float inspection. Because corrosion inside of tanks is generally worst at the roof level, interior inspections are often most effective when performed from a properly sanitized inflated rubber raft. This allows a close inspection of corrosion and related structural details (Figure 5.18). Temporary repairs of small areas can also be performed during the inspection. Dive inspections. Many companies offer underwater inspection services, including sediment vacuuming, video recordings, and spot repairs by specially trained divers. Coating thickness measurements. A dry-film thickness gage is used to measure the thickness of the remaining coating, per SSPC-PA2, Measurement of Dry 81 As discussed in Chapter 4, the frequency of cleaning should be determined by measurement of results. 82 NACE International, the professional society of corrosion engineers provides training and certifies coating inspectors and cathodic protection professionals

156 Answers to Challenging Infrastructure Management Questions Coating Thickness with Magnetic Gages. This is done on the interior and exterior of roof and wall shells and at various points on beams and rafters. Steel thickness measurements. The thickness of roof plates, floor plates, and wall shells are measured using UT gages. This is helpful in measuring corrosion losses and also in determining the baseline thickness of materials, which are often not shown on the as-constructed drawings. The baseline thickness is needed for a structural assessment, including a seismic evaluation. The depths of pits are measured using pit gages. Source: Photos by HDR Figure 5.18. Example of tank float inspection. This coating is not very old, but a float inspection revealed workmanship problems missed during a dive inspection. Blistering. The degree of coating blistering is evaluated per ASTM F714, Standard Test Method for Evaluating Degree of Blistering of Paints Paint chalking. The degree of chalking is evaluated per ASTM D4214, Standard Test Methods for Evaluating the Degree of Chalking of Exterior Paint Films. This is helpful in determining when a polyurethane or other top-coat may be needed to help preserve the existing paint. Chalky paint is more porous, leading to corrosion of the underlying steel. Field adhesion testing. This is performed per ASTM D3359, Standard Test Methods for Measuring Adhesion by Tape Test, and involves cutting an X in the surface using a sharp knife, and observing how much paint is removed. This test determines whether an existing coating can be cleaned and top-coated, or whether blasting to bare metal is needed. The test is destructive, so coating repairs are needed at the points where the tests are conducted, if the tank will not be recoated soon. Cathodic protection system evaluation. The functionality of existing systems should be verified by a CP specialist, including a determination that the electrical potential is sufficient to provide protection.

Chapter 5 Condition Assessment 157 Current requirement testing. The current density is calculated using the amount of current required and the area of the wetted surface. This provides a direct measurement of how much unprotected steel is exposed to water and thus gauges the effectiveness of the existing submerged coating. Field test for lead. Commercial testing kits can provide a quick, qualitative test for the presence of lead (Figure 5.18). Field sampling for lead. If lead is confirmed or suspected, samples should be taken to determine the concentration levels. Sampling should be performed, per ASTM E1729, Standard Practice for Field Collection of Dried Paint Samples for Subsequent Lead Determination. Laboratory testing for heavy metals. Before any recoating project is undertaken, the concentration of heavy metals (lead, chromium, and zinc) in the existing coatings should be tested, per EPA methods 7420, 7190, and 7950. Concrete Tanks and Reservoirs For concrete tanks, the primary concerns are cracks. If significant cracks are identified, an evaluation by a knowledgeable structural engineer is needed (see Chapter 3 for discussion regarding cracks). Both a float inspection and a dry inspection may be required. Additionally, leakage from the reservoir can be evaluated by shutting valves and/or plugging outlet pipes and measuring the change in water level, applying American Concrete Institute Standard 350.1, Tightness Testing of Environmental Engineering Concrete Structures and Commentary. Health-Issues and Other Concerns do not exist: All tanks and reservoirs should be inspected to confirm that undue risks to public health Vents and other openings should be well screened with both fine and coarse mesh to keep out insects and rodents. From the inside, very little daylight should be visible. Hatches should be well secured with tamper-resistant locks, supplemented with entry alarms Sites should be well secured, with appropriate fencing, lighting, signage, and alarm systems Air gaps should exist between overflow/drain pipes and site drainage facilities. Pipes should be screened to prevent rodent and insect entry. Roofs should be well draining, so that dirt and other contaminants are not carried into the tank by rainfall. Sites should be well draining so that corrosion is not aided by ponded water and soil next to the tank. A drainage system or free draining material should keep water away from the underside of steel tanks. A sound structural envelope should be maintained. Inside, there should not be flaking, pealing coatings, and decaying wood materials. Interior coatings should be free of lead and other heavy metals. Accumulated sediment in the bottom of the tanks should be periodically removed.

158 Answers to Challenging Infrastructure Management Questions Inlet and outlet piping should be configured so that mixing of contents occurs, reducing the risk of nitrification in chloraminated systems, as well as other water quality risks. HOW SHOULD PUMP STATIONS AND TREATMENT PLANTS BE EVALUATED? Evaluation of pump and treatment facilities frequently involves a multi-discipline team, examining conditions, code compliance, and performance issues, as shown in Table 5.2: Discipline Architecture Structural Corrosion Mechanical Process Table 5.2. Assessments of Pump Stations and Plants Evaluations Fire safety, exits, ADA access Hazardous materials (asbestos, lead) Roofing and waterproofing Thermal insulation LEED (Leadership in Energy and Environmental Design) evaluations Structural condition (per SEI/ASCE Standard 11, Guideline for Structural Condition Assessment of Existing Buildings) Seismic resistance Analysis of distressed structures and structural failures Material condition (concrete, steel, iron, etc.) Coating condition CP system function Corrosion activity HVAC systems and controls Plumbing systems Pump efficiency, performance, vibration Transient pressure (surge) protection Condition and operability of valves Treatment process functionality and efficiency Records and documentation Regulatory compliance (continued)

Chapter 5 Condition Assessment 159 Discipline Electrical Instrumentation and Controls Table 5.2. Assessments of Pump Stations and Plants Evaluations Code compliance Safety / arc flash / grounding / surge protection Emergency power Energy efficiency Condition of electrical equipment and components Process operations and controls Communications systems (primary and secondary) Data capture and storage, including backup Uninterruptable power supply (Continued)

CHAPTER 6 PIPELINE RENEWAL METHODS What is the best way to renew a water system? Pipeline rehabilitation and other trenchless methods of water main renewal offer many advantages over traditional open-trench construction. They are less disruptive to the community, are generally less costly, and can usually be accomplished more quickly. However, pipe rehabilitation and other trenchless methods also have limitations, including uncertainties about the structural values and life expectancies these methods provide. Moreover, not every pipe can be successfully rehabilitated. If the rehabilitation of a main would require numerous access excavations due to bends and lateral connections, open-trench construction may be the most viable option. Additionally, opentrench provides an owner with a wide range of choices regarding materials, pipe size, and pipe location. This chapter provides an overview of the common renewal alternatives that are available, with a focus on trenchless technology because it is not as well understood and appreciated as traditional construction methods. As engineers have become more exposed to these methods, as new technologies have been introduced, and as new companies have entered the market place, more and more utilities have used these methods successfully for both special applications and general infrastructure programs. IF PIPE REHABILITATION IS SO GREAT, WHY ISN T IT USED MORE? Pipeline rehabilitation is widely used today but in the wastewater industry. In the water industry, it is less common. This difference between wastewater and water industry acceptance rates is at least partly the result of differences in knowledge levels and expectations. In non-pressurized wastewater pipe, the conditions of the mains are readily understood. Their interiors are easily assessed, using video and other equipment inserted at manholes, following an industry standard procedure. 83 Rehabilitation methods are then selected based on a direct assessment of the pipe, with guidance from an ASTM standard. 84 As a result, the final product is well understood, and rehabilitation using cured-in-place pipe (CIPP) lining is now far more common than open-trench replacement for renewal of wastewater pipes. In the water industry, the story is quite different. Here, the conditions of mains are generally not known but are only inferred, using leak history, occasional sampling, age, and other data. Direct assessments are generally not used because they are considered too costly getting a NDE tool in and out of an active water main is often thought too difficult. Even when NDE is performed, the interpretation of data can be difficult. If a corrosion pit has penetrated 40 percent of the pipe wall, is that a cause of action? And if action is warranted, what exactly should be done? Currently, a water utility wishing to perform a structural rehabilitation has virtually no standards to use for the design of the lining. Is it any wonder that water main rehabilitation in the US is still considered unusual? 83 The Pipeline Assessment and Certification Program (PACP) established by the National Association of Sewer Service Companies (NASSC) guides the video inspection of gravity sewers, providing standard defect codes and training and certification for inspectors. 84 ASTM F1216, the standard used for design of CIPP lining of gravity pipe, considers essentially two cases: (1) the lining must resist all loads (fully deteriorated pipe) and (2) the lining must resist only the external water pressure (partially deteriorated pipe). 161

162 Answers to Challenging Infrastructure Management Questions WHAT DOES A TYPICAL REHABILITATION PROJECT INVOLVE? A typical lining process entails the following basic steps: 1. Bypass piping system. A bypass piping system is installed, disinfected, tested, and put into service, providing water to customers during the duration of the project. The old water main is valved off (removed from service). 2. Access pit excavation. Access pit locations are laid out, conflicting utilities are marked, and excavations made. Pits are generally required at elbows, bends, tees, and valves, and spaced no more than about 500 feet apart. These pits are covered with traffic plates, when work is not actively occurring. 3. Pipe access and dewatering. A section of pipe at each end of the run is removed, along with adjoining fittings and valves, providing access to the pipe. Water is pumped from the excavation. 4. Cleaning. A rodding truck pushes a snake through the pipe, which is then used to pull back a wire rope. The pipe is mechanically cleaned using either a drag scraper pulled repeatedly through the pipe, or a rack-feed power boring machine (a flailing device). The mechanical cleaning is followed by squeegees and possibly swabs, to remove sediment and water. 5. Cleaning inspection. Video inspection may then be used to confirm that the pipe is sufficiently clean. This is important for a polymeric lining system less so for most other systems. 6. Lining. The pipe is lined using a rotating sprayer or by pulling in a liner. 7. Lining inspection. Video inspection may then be used again, to confirm that the lining was done correctly. This again is important for polymeric linings, but less important for other linings. 8. Pipe closure. The removed sections of pipe will either be hand cleaned and lined, or replaced with new materials. The pipeline is closed, generally using mechanical couplings, and checked for leaks. 9. Recommissioning. After curing, the pipe is flushed, disinfected, tested, and returned to service. Laterals are reconnected to the main and flushed. 10. Clean-up. Excavations are backfilled and repaved. Bypass piping systems are removed. There is of course much more involved, like preparing plans and specs for bidding, obtaining permits, and communicating with the public. Some of these aspects are further discussed in Chapter 7. WHAT METHODS SHOULD I USE FOR PIPELINE RENEWAL? Table 6.1 lists the common water main rehabilitation technologies. Each of these methods is appropriate for the rehabilitation of water mains, depending on the structural condition of the existing pipe, and other considerations. The selection of which system to use will also depend on cost, owner preferences, and other factors. All materials in contact with water must be tested and certified in accordance with ANSI/NSF61 requirements.

Chapter 6: Pipeline Renewal Methods 163 Table 6.1. Common Water Main Rehabilitation Methods Description Advantages Limitations Cement mortar lining, spray-applied, in situ (ANSI/AWWA Standard C602) Low cost Time-tested protection against internal corrosion Service reconnection not required Non-structural not recommended if pipe is structurally deficient Not recommended where water is soft Polymer lining, 1 mm thick (epoxy, polyurethane, or polyurea), sprayapplied, in-situ (ANSI/AWWA Standard C620) Low cost Time-tested protection against internal corrosion Service reconnection not required Rapid set-up of some linings may allow same-day return to service (avoiding bypass system costs) Non-structural not recommended if pipe is structurally deficient Polymer lining, 3 to 8 mm thick (epoxy, polyurethane, or polyurea), sprayapplied, in-situ Moderate cost Semi-structural proven ability to span holes and gaps. Service reconnection not required Not likely to survive fracturing of the pipe Ability or serve as fully structural system has not been confirmed Rapid set-up of some linings may allow same-day return to service (avoiding bypass system costs) Cured-in-place pipe lining, reinforced with fiberglass, polyester or carbon fibers Fully or semi-structural Appears capable of surviving pipe fracture Robotic service restoration is possible in many cases More costly than spray-applied linings Service reconnections are required (continued)

164 Answers to Challenging Infrastructure Management Questions Table 6.1. Common Water Main Rehabilitation Methods Description Advantages Limitations (Continued) Tight-fit HDPE slip lining, using rolldown, swage, or deformed methods Semi- or fully structural Capable of surviving pipe fracture Design criteria and properties are well established More costly than spray-applied linings Service reconnections are required Limited wall thickness available Pipe bursting replacement Fully structural Some upsizing possible More costly than most other methods, although competitive market exists (not proprietary) Design criteria and properties are well established Service reconnections are required Compared to tight-fit lining, pipe materials should be more easily procured (less critical sizing requirements and different materials can be used) The rehabilitation techniques listed here are methods that have proven their effectiveness in water main rehabilitation. Many other techniques are promoted, but not all are effective, efficient, or durable. Method selection depends on many site-specific factors, including the structural integrity of the host pipe, the locations and numbers of valves, laterals, and connections, future system plans, and the owner s preferences. AWWA Manual M28, Rehabilitation of Water Mains, includes decision trees that can guide the selection. Typically, a pipeline rehabilitation project will concurrently include upgrades or replacements of valves. It may also be a good time to consider installing or replacing hydrants, meters, and substandard service laterals, particularly those with lead pipe. In-Situ Cement Mortar Lining Cement mortar lining (Figure 6.1) is arguably the oldest pipe rehabilitation methods. Hand applications of mortar to pipes date to the 1920s. Machine applications date to the 1940s. The benefits of cement mortar lining are indisputable. The lining provides a highly alkaline environment next to the metal that virtually eliminates corrosion of the interior surface. This in turn eliminates the formation of iron mineral deposits (tuberculation) that choke off flow, waste energy, and lead to water quality complaints and concerns.

Chapter 6: Pipeline Renewal Methods 165 Source: Photo courtesy L.A. Department of Water & Power Figure 6.1. Cement mortar lining (before and after) While the ability to line pipe in place has existed since the 1940s, only a handful of companies perform this service, which requires specialized equipment. The cost to clean and cement mortar line pipe in place ranges from one quarter to one half the cost to replace it, depending mostly on the size of the pipe, the complexity of the system, and the size of the project. Small projects are less economical, due to mobilization costs. Since the lining virtually stops interior corrosion, the life of most pipes will be extended considerably no one is sure how much. This is because in the absence of corrosive soils, very little in-situ lined pipe has failed, even after 50 years. We do know that cement lining causes leak rates to drop dramatically. On a major pipeline in Los Angeles, for instance, 220 leaks were recorded in the pipeline s first 58 years, but only 2 in the next 35 years after it was lined. Epoxy and Other Polymer Linings In areas where water is extremely soft, deterioration of cement mortar lining can occur. 85 For this reason, in Britain, polymer linings (Figure 6.2) are commonly used instead. Britons also tend to have smaller diameter pipes, where the economics of epoxy lining are more favorable. The first polymer lining, epoxy, dates to the 1980s. In addition to epoxy lining, other polymer lining materials have been used, including polyurethane and polyurea. The advantages of these linings are very fast cure times, allowing the pipe to be repressurized in just a few hours. This enables the rehabilitation of distribution pipes without the need for bypass piping (see discussion later in this chapter). It also enables thicker linings to be applied in a single pass, without sagging. 85 Generally, if alkalinity is less than 55 mg/l (as CaCO 3 ), then in-situ cement mortar lining should not be used. For more information, see Douglas and Merrill 1991.

166 Answers to Challenging Infrastructure Management Questions Source: Photo courtesy HydraTech Engineeered Products, LLC. Figure 6.2. Epoxy lining (before and after) Structural Liners/Trenchless Replacement Although it was said earlier in this chapter that cement mortar lining was arguably the oldest rehabilitation technique, sliplining must be older. No doubt someone many, many years ago slipped a smaller pipe inside a larger one, as a means of avoiding trenching. Because of the popularity of this method, virtually all pipeline materials are now available in a style that facilitates sliplining, with either fused joints or low-profile couplings. Steel plates have also been used to line large-diameter pipes. Rolled steel plates are maneuvered and jacked into position inside the pipe; then following welding, the annulus is grouted. The last step in the process is in-situ cement mortar lining of the steel pipe. This method is costly, but is often less expensive than replacing a large-diameter pipe that is deep underground. HDPE Sliplining High-density polyethylene pipe is a particularly appropriate material for sliplining water pipes. Because it is both flexible and ductile, the construction is simpler and less risky than for other materials. Scratches and gouges in the material are not likely to lead to cracks, and rapid crack propagation is not likely to occur. Additionally, corrosion protection is not an issue. As with most sliplining, this method is really a replacement technique rather than rehabilitation. The end product is a new pipe that is structurally independent of the host pipe. Segments of HDPE pipe are fused together, above ground, into a single pipe string. Then the HDPE pipe is pulled inside the host pipe between access pits (Figure 6.3). While steel, ductile iron, PVC and fiberglass pipe can also be used for sliplining, HDPE is particularly suitable because of its crack resistance, flexibility and fully fused joints. 86 In most instances, the annulus between the host pipe and new pipe is grouted with slurry or cellular concrete. This further stabilizes the pipe and keeps water from traveling through the annulus. 86 There are differences of opinion regarding whether the annulus area between pipes should be grouted. Grouting adds substantially to the cost of the installation.

Chapter 6: Pipeline Renewal Methods 167 Source: Photo courtesy of J. Fletcher Creamer & Son, Inc. Figure 6.3. HDPE Sliplining The prime disadvantage of using HDPE is that its relatively low strength results in thick walls and a smaller inside diameter. The outside diameter of the new pipe must be either about 10 percent or two inches smaller than the inside diameter of the existing pipe to facilitate insertion. Moreover, many owners are also reluctant to use HDPE due to unfamiliarity with the material and uncertainties about how to repair it and connect to it. While these concerns are legitimate, technical solutions exist, but training, equipment, and emergency inventory changes may be required. Fused PVC Sliplining Specially-formulated, fused PVC pipe was developed in the mid 1990s for a tight-fit lining application (as discussed below), but has seen considerable use as an alternative to HDPE for sliplining and similar trenchless applications. Because PVC is a stronger material than HDPE, thinner-walled pipes can be used, resulting in greater hydraulic capacities. The greater strength has also allowed for longer runs between entry and exit pits, particularly in horizontal directionally drilled (HDD) applications. Many owners also prefer this material because they are familiar with it, and already have fittings and couplings that are compatible. PVC also has disadvantages in trenchless applications that need to be considered. Because it is a more brittle material than HDPE, there s a greater likelihood that scratches and gouges might eventually produce cracks. Cracks also can propagate through PVC and can travel for hundreds of feet, if joints are fused. Tight-Fit HDPE Lining The capacity reduction associated with conventional sliplining can be largely solved by using tight-fit HDPE lining. While similar to sliplining, this procedure utilizes a larger-diameter, thin-walled HDPE pipe. (The OD of the liner is approximately equal to the ID of the host.)

168 Answers to Challenging Infrastructure Management Questions The construction process is virtually identical to conventional sliplining, except the pipe is pulled through either a die or a series of rollers, that temporarily reduces its diameter just before it is inserted. Then, once in place, the liner pipe slowly expands, returning to its original size, fitting snugly within the host pipe. A variation to this approach uses a device to deform the liner pipe into a U shape, which is secured with plastic bands (Figure 6.4). Once the liner pipe is in place, the bands are broken as the pipe is inflated using air pressure, fitting snugly within the host pipe. Source: Photo courtesy of HDR Figure 6.4. Deforming a 24-inch HDPE pipe for tight-fit HDPE lining Whichever method is used, the HDPE liner pipe must be relatively thin in order to deform it for insertion. Because the liner is in contact with the existing pipe, the liner/host product behaves as a composite. While the plastic liner adds negligible hoop strength to the existing pipe, it is capable of spanning across holes and other weak areas in the host pipe. It also stops interior corrosion. Neglecting the strength that the host pipe provides, the stand-alone pressure rating for a tight-fit HDPE pipe is typically about 50 psi. 87 The chief disadvantage of tight-fit lining is its novelty. The techniques and hardware (fittings and couplings) are not fully developed, and only a few contractors are experienced in this method and have the requisite equipment. Also connecting to or repairing a tight-fit lined main will generally entail cutting in a complete fitting or spool section. A conventional tap will not work. Reinforced Tight-Fit HDPE Lining A recently introduced product in the oil and gas industry may have great potential for the rehabilitation of water transmission mains. While similar to the deformed tight-fit method just described, this method provides a stand-alone structural lining system capable of pressure ratings 87 With the strength of the host pipe included, the pressure rating would be essentially equal to the host pipe strength, assuming that holes and weak areas in the host pipe are only a few inches in diameter.

Chapter 6: Pipeline Renewal Methods 169 up to 1000 psi. 88 This is achieved by reinforcing the exterior of the liner pipe with high-strength fabrics. The composite product is manufactured in the field using portable equipment, and includes axial reinforcement to enable long pulls, and an acoustical fiber optic cable for leak detection. The maximum diameter is currently limited to 16-inches, but if applications in the water industry develop, the manufacturer has indicated a willingness to develop equipment capable of producing larger diameters. Because it is difficult to connect to this composite material, it is only suitable for transmission lines without lateral service connections. Tight-fit PVC Lining This product looks similar to tight-fit HDPE sliplining, but the method of producing it is quite different. The process starts by fusing PVC into a string, then pulling it into a pipe, like a conventional sliplining (the OD of the liner is smaller than the ID of the host). After the liner pipe is installed, it is heated by circulating steam through it. When the PVC material reaches a certain temperature, pressure is applied and the liner stretches until it fits snugly inside the host pipe, at which point the pressure is maintained, while the pipe is allowed to cool. The manufacturer claims this product provides a fully structural lining, with stand-alone pressure ratings similar to other PVC water pipes. Further, it is claimed that as the material expands, the molecular structure of the PVC changes, creating greater strength and toughness, similar to how oriented PVC pipe (PVCO, ASTM 1483, AWWA C909) is produced. Unlike PVCO pipe, however, the method used to produce tight-fit PVC lining does not always produce a material with uniform thickness. 89 Pipe Bursting Like sliplining, this technique is really a pipe installation method. The advantage of pipe busting is that no reduction in capacity is required in fact the pipe size can often be increased, within limits. Again, the technique resembles sliplining; however, a bursting tool is inserted in advance of the new pipe (Figure 6.5). The bursting tool breaks the existing pipe and expands the opening, enabling a larger pipe to be simultaneously pulled into place. Tools have been developed that split clay and cast-iron pipes with ease. Concrete pipe has also been burst, but the steel reinforcement can be a concern. In the last decade, tools capable of splitting steel and ductile-iron pipes have been deployed very successfully. 88 The method is covered under ASTM 2896-11, Standard Specification for Reinforced Polyethylene Composite Pipe For The Transport Of Oil And Gas And Hazardous Liquids. 89 The lining method also does not achieve the same degree of expansion, nor axial elongation, so should not be automatically considered equal to AWWA C909 pipe.

170 Answers to Challenging Infrastructure Management Questions Source: Illustration courtesy of TT Technologies Figure 6.5. Pipe bursting The amount of upsizing that can be achieved through pipe bursting is a matter of site conditions the compressibility of the soil, the depth of the pipe, and the proximity to other utilities. A risk associated with pipe bursting is heaving of the soil, and consequent damage to pavement and other utilities. Pot holing to expose any utilities of concern is recommended prior to starting the bursting process. Also, the greater the upsizing, the slower the process, and the more the pipe might be gouged as it is pulled through the ground. The gouging of the pipe is a concern to many engineers. When pipe bursting was initially used, some engineers insisted that casing pipes be installed to protect the carrier pipes. The casing pipes would be pulled into place using the bursting tool, and then the carrier pipes would be slipped into the casing. This more expensive two-pipe approach is seldom used today. Typical specifications allow gouges up to 10 percent of the wall thickness, and an examination of the leading portion of the pipe generally indicates that the gouges meet this standard. 90 As the leading edge of the pipe is pulled into the exit pit, the degree that gouging has occurred can be accessed. In the last decade, pipe bursting acceptance has grown tremendously as more contractors have gained experience and more owners have seen its effectiveness and cost benefits. As an example, WaterOne, the utility that serves several communities in the Kansas City suburbs, decided to try pipe bursting for routine water main replacement, using their own construction crews. The utility hoped that pipe bursting would produce cost saving of about 15 percent, by reducing the amount of repaving that would be required. In reality, the cost savings approached 25 percent, because more work could be completed each day. When it works well, pipe bursting construction is remarkably easy. The method is especially cost-effective where physical constraints to conventional cut-and-cover installation exist. 90 A new product being used in Europe provides additional insurance against gouges, using a tough polypropylene skin to protect the HDPE. (The skin and pipe are extruded simultaneously.)

Chapter 6: Pipeline Renewal Methods 171 Reinforced Cured-in-Place Pipe (RCIPP) Cured-in-place pipe (CIPP) lining is a very common technique, used primarily in the wastewater industry to rehabilitate pipe. In this method, a resin-impregnated fabric tube is inverted within the host pipe using air or water pressure. The resin is then cured using steam, hot water, or UV light. The product forms a composite with the existing pipe. The major difference between reinforced CIPP and traditional CIPP is the fabric tube that is used. RCIPP uses a woven jacket made from polyester, fiberglass, Kevlar or carbon fibers instead of simple felt. The types and amount of reinforcement are determined by liner loading requirements. Pressure pipe CIPP liners are commonly available in pressures up to 150 psi, and can be custom-designed for higher pressure. RCIPP has been used in pressure pipes up to 72 inches in diameter. Polyester Reinforced Polyethylene (PRP) When delivered to the job, this product looks much like a fire hose. It arrives flattened, on reels, and is simply pulled into the host pipe. The polyester fabric reinforcement provides the strength to resist high pressures. Unlike a fire hose, however, the product is very stiff, with a polyethylene lining and coating. Once in place, the liner is temporarily softened and inflated using steam. PRP does not bond with the host pipe; it is designed to resist 100 percent of the internal pressure by itself. Since the PRP pipe is thin and flexible, the host pipe is still needed as a casing to resist the compression loads from the soil, particularly for the times when the line is out of service. This liner is available for pipe sizes up to 12 inches in diameter. Joint Sealing Internal seals provide a cost-effective method for eliminating leaking pipe joints in all types of large pipe, including cast iron, ductile iron, concrete, steel, vitrified clay, and plastic, in sizes 16-inches and larger. Standard seals are effective against pressures up to 300 psi, and higher pressures have been accommodated with special designs. Seals for water pipe are installed through man-entry (Figure 6.6), although robotic methods are currently available for installing similar devices in wastewater pipe. In addition to sealing gaps in joints, seals can also be used to bridge over cracks in the pipe and seal off abandoned branch and service connections. Access for entry to pipelines can be as much as 5,000 feet apart, requiring minimal if any excavations.

172 Answers to Challenging Infrastructure Management Questions Source: Photo courtesy of J. Fletcher Creamer and Son, Inc. Figure 6.6. Internal Joint Seal HOW DO I CHOOSE AMONG THE VARIOUS LINING METHODS? The choice of rehabilitation system depends on many factors: Is the existing main structurally impaired? If so a structural or semi-structural method is needed. What hydraulic capacity is required? Most methods will result in improved hydraulics, but significant differences exist between the various alternatives. How many service laterals exist? Little to no effort is required at service laterals, if a spray-applied, adhered lining is used. For other methods, robots may be required to reinstate the lateral opening, or an excavation may be needed. How many fittings and valves exist? In most cases, an excavation is required at each elbow, tee and valve, although there are exceptions. This is true regardless of the method used, although spray-on linings can be applied through some fittings. Can the lining be accomplished with a bypass system? In an ideal world, the pipe can be shut down for several days while it is rehabilitated, but in most cases, a bypass piping system (as described below) is required. Strategies to avoid the bypass piping have been successfully employed elsewhere, using quick setting polymer linings, and pre-sanitized liners. What skills and equipment are needed for installing the system? While some methods require the mobilization of specialized equipment and crews, other methods can be installed using local equipment and normal pipe laying crews. AWWA Manual M28, Rehabilitation of Water Mains, includes decision trees that can guide the selection of a system. In general, the cost of a rehabilitation project will be most affected by the number of excavations required.

Chapter 6: Pipeline Renewal Methods 173 WHAT OTHER REHABILITATION ALTERNATIVES EXIST? Cathodic Protection Retrofits Large-scale retrofits of cathodic protection (CP) systems are normally only installed on welded or riveted steel pipe. However, any electrically continuous pipe can be cathodically protected. Pipes have also been retrofitted so they become electrically continuous. On large pipelines, this is accomplished with Z bar, which are bonds welded across the joint on the inside of the pipe. On smaller pipes, vacuum excavation and keyhole tools have been used to install exothermically welded jumper cables across the joints. On small pipes, where only small current flows are needed, a sacrificial (galvanic) system is usually used. A magnesium anode will be buried near the pipe and becomes a sacrificial element. Periodically, perhaps every 20 years, the magnesium must be replaced. Galvanic systems are also appropriate where joint bonding is not 100 percent. While the anodes won t protect pipe beyond an electrical discontinuity, they also will not cause electrolytic corrosion at the point of discontinuity Where large current flows are needed to protect a large pipe that has minimal coating, an impressed current system is often more appropriate, with a rectifier delivering a DC current through a deep-well anode. Design of such systems requires the expertise of a specialist. The design must carefully account for soil resistivity, the corrosion rates of the pipe, and the presence of other buried infrastructure that both interferes with and can be damaged by the impressed current. CP reverses the natural current flow produced by electrochemical corrosion, stopping nearly all external corrosion of metal pipes. When installed as part of the original construction, CP systems typically cost less than one percent of the construction, yet extend the expected life of the pipeline indefinitely. As a retrofit to existing pipelines, CP can offer similar benefits, if the pipe is suitable. A pipe that is a good candidate for a CP retrofit will have the following characteristics: Electrically continuous joints. Welded and riveted steel pipes are electrically continuous. Rubber-gasket joints are not. Old cast iron pipe is probably not electrically continuous, but it depends on the material used to caulk the joints, and how much oxidation has occurred on the abutting metal surfaces. If a pipe is not electrically continuous, it can be made continuous, by bonding jumper cables across the joints as you would do for a new pipe, but the cost to install these cables on an existing pipe, make a CP retrofit less attractive. Good dielectric coating. If the pipe is well protected by a coating that insulates it from the soil, only a small current will be needed to provide cathodic protection, and anodes can be spaced well apart. With poorer coatings, more current and a larger number of anodes will be needed. Electric isolation from other pipes. A pipe that is to be cathodically protected must be electrically isolated from everything else, with insulating joints (IJ s) needed at connections to other mains, and service laterals. The cost to install insulating joints can be a large part of any retrofit. A transmission main, with few interconnections and no service taps, is thus a good candidate for CP.

174 Answers to Challenging Infrastructure Management Questions CP retrofits come in different flavors, from small and routine, to large and complex. Many utilities routinely attach magnesium anodes whenever a repair is made to a steel or iron pipe. Other utilities have undertaken programs to retrofit nearly all suitable pipes within their systems. A case of an aggressive, successful crash program is the Marin Municipal Water District of Northern California which reported a savings of $1.4 million annually following a system-wide program that reduced the number of leaks from over 1300 per year to about 500 per year (Harrington, 1985). Likewise, the City of Des Moines used keyhole methods (as described below), to install sacrificial anodes at a cost of roughly $10 per foot of main. The City estimated that a 20-year life extension was achieved at less than 10 percent of the cost of main replacement (Klopfer and Schramuk, 2005). As discussed in Chapter 5, the City of Calgary credits a program of CP retrofits guided by electromagnetic scanning for a 50 percent reduction in main breaks over the last 15 years. Spot Repairs and Segment Replacements Often, only a small area or a few segments of pipe will be badly deteriorated even on a problematic main. With remote-field EMT and other assessment methods, we can now see underground and focus our efforts on these areas. This can save money compared to larger scale replacements, and may also entail fewer service interruptions and less disruption to the neighborhood. These rehabilitation repairs differ from those performed by the typical main repair crew. Whereas the repair crew is mostly concerned with restoring service, rehabilitation aims to restore the pipe s strength to a like-new condition. The condition should thus be assessed, the repair engineered, and the completed work inspected in a planned, systematic manner. The focus is on restoring long-term structural integrity. Although rehabilitation repairs may use clamps or similar repair methods, the complete removal of a bad section of pipe may also be performed. In the last decade, spot rehabilitation repairs of large diameter pipes with carbon fiber reinforced plastic have become fairly common. Layers of fibers are pasted on the inside of the pipe, using epoxy resin. The application method looks like hanging wall paper except that multiple, overlapping layers are applied. Ultimately, a fiber-reinforced plastic pipe is built within the host pipe, either as a composite or capable of resisting the full pressure force. 91 As you can imagine, the carbon-fiber method can be expensive but so are the alternatives (including a rupture). The advantage of this approach is that no excavations may be needed. Materials can be inserted though the existing access holes. Other spot repairs for CIPP have included external reinforcement using prestressed steel tendons or steel sleeves. CAN REHABILITATION STRENGTHEN THE PIPE? Conventional pipe rehabilitation design does not attempt to share loadings between host pipe and the lining. The host pipe is assumed to carry the entire load or none of it. This assumption is convenient because it avoids the issue of strain incompatibility. Iron is approximately 30 times stiffer than the stiffest unreinforced polymers, meaning that very little 91 One concern with internal structural liners is achieving good seals at the ends of the liner. If water gets behind the liner, it can become virtually useless in resisting pressure.

Chapter 6: Pipeline Renewal Methods 175 stress (and loading) can be taken by a plastic lining material, until the host pipe strength is nearly gone. WaterRF Project No. 4095, Global Review of Spray-On Structural Lining Technologies (Ellison, et al., 2010) discusses at length the issue of when a spray-applied polymer lining might be considered fully structural. With a thick application of a high-strength polymer, sufficient hoop strength may exist for the lining to provide stand-alone pressure resistance, but the mechanism by which hoop stress would transfer from a stiff host pipe to a more flexible lining is not clear. If the lining is well adhered to the host pipe, very high local strains could occur when the host pipe fractures, causing tearing of the lining. Source: Photo courtesy of Louisiana Tech University Figure 6.7. Pipe bending test of CIPP lining under pressure In tests performed at Louisiana Tech s Trenchless Technology Center, a reinforced cured-in-placepipe lining appeared to demonstrate the ability to survive the fracturing of the host pipe, while withstanding 120 psi of internal pressure without leakage. Where the lining material is reinforced with fabric, the strains of the lining and substrate materials may be more compatible, and the sharing of loads between the host pipe and lining is more likely (although the interaction might be complex). With fabric reinforcement, the ability of a lining to resist tearing is also much more likely. This has been confirmed through testing of a CIPP lining at the Louisiana Tech University s Trenchless Technology Center (Figure 6.7). HOW DO I DESIGN A PIPE LINING? To design a lining, the first question is what structural benefits are needed. If the existing pipe has never leaked, perhaps a non-structural lining is sufficient. If the pipe is in poor condition, a fully structural method may be needed. And if the pipe is somewhere in between, maybe a semi-structural method will suffice. AWWA has standards for main rehabilitation using cement mortar (ANSI/AWWA 602) and thin (1 mm) epoxy lining (ANSI/AWWA C620). Both are considered non-structural, so these standards are for the lining installation rather than for structural design. Although several standards are in draft form, AWWA currently has no standards for the design or construction of other rehabilitation systems providing structural or semi-structural solutions. AWWA Manual M28, Rehabilitation of Water Mains groups lining systems into four categories based on their structural benefits, but the definitions are broad and open to some interpretation. As a manual of practice, M28 is not intended to serve as a design standard.

176 Answers to Challenging Infrastructure Management Questions Non-Structural lining design The definition of a non-structural lining is apparent. Although these linings have minor structural value, the benefits are considered negligible. Non-structural linings are applied for hydraulic, water quality and corrosion protection benefits only. Design of Fully-Structural Rehabilitation A fully-structural method, on the other hand, implies that the finished product is equal to a new pipe. Therefore it should be designed in the same manner as someone would design a new pipe, applying AWWA standards or if none exist, the principles inferred from AWWA standards. For instance, the design of a plastic pipe material should be based on applying a safety factor of 2 or greater to the 100,000-hour strength of the material. 92 A structural lining must also possess two additional properties: (1) it must be positively connected to laterals and other intersecting pipe and (2) it should have the ability to withstand a fracture of the host pipe. Without the first property (a connection between liner and lateral), water will get into the annulus between the liner and host pipe, and the structural (and other) benefits of the liner are lost. Without the second property (the ability to survive a fracture), the product cannot claim new pipe equivalence, since a crack in the host pipe could cause failure at any moment. Semi-Structural Lining Design The definition of a semi-structural lining is currently pretty hazy. While the M28 Manual defines semi-structural linings as having the ability to span holes and weak areas in the host pipe, there is no definition regarding the size of the hole, the pressure that must be sustained, the amount of time it must be sustained, or the safety factors that are applied. By this loose definition, even cement mortar and thin polymer linings can claim to be semi-structural, as tests have shown their abilities to span holes. In conventional gravity-pipe rehabilitation, ASTM F1216 provides a clear design standard for semi-structural lining. In this standard, two design cases are used: (1) partial deterioration and (2) full deterioration. The definition of partial deterioration is that the existing pipe resists the soil pressure and surcharge loads (for the design life of the pipe), and a liner withstands only the groundwater pressure. For a fully-deteriorated pipe, the liner must be designed to resist both the soil and groundwater pressures, as though the host pipe did not exist. This simple definition is convenient, because it avoids the necessity of proportioning loads to the liner and host pipes, and avoids the issue of strain compatibility (as discussed earlier). A spray-applied lining has the advantage of not plugging the service connection, and thus not requiring extra effort for reconnection of the lateral. But how structural is a spray-applied lining? More research is needed before this question is answered. Unless spray-applied linings can demonstrate their ability to survive pipe fracturing, they should not be considered fully structural. What really are the properties required for such a lining and how should it be designed. The answers to these questions are the subject of a current WaterRF project (No. 4473). 92 This is the hydrostatic design basis found in AWWA standards for PVC, HDPE, and other types of plastic pipe.

Chapter 6: Pipeline Renewal Methods 177 HOW DO THE VARIOUS LINING MATERIALS PERFORM? Cement Mortar Linings As discussed in Chapter 3, the high-ph corrosion protection provided by CML eventually goes away, and because field-applied linings are less dense, this occurs more quickly for rehabilitated than for shop-lined pipe. There have been several cases where cement mortar linings of large pipelines have needed replacement or repair, but these are generally the exception, not the rule. For the most part, there is little evidence that field-applied linings in smaller mains have failed, even after 50 years. While a thin layer of corrosion is often found beneath the lining, turbercles and spalls are rarely found. Non-Structural Polymer linings Deb, et al., (2006) studied the life expectancy of epoxy linings, and concluded that a 50 to 60-year service life could be expected, when the lining was constructed properly. This observation should be equally applicable to non-structural polyurethane and polyurea linings. Deb found hat poor construction and lack of QA/QC procedures resulted in holidays (pinholes) and significant variations in dry film thickness, both of which can have a negative impact on the longevity of a polymer liner. Other problems included: problems with polymer set-up/cure and uneven advancement of the lining machine. A large amount of experience with polymeric coatings would indicate that holidays and flaws will always exist. Ellison, et al., (2010) noted that corporation stop ferules protruding into the pipe often create shadows where spray-applied linings are either thinly applied or completely missing. Uncoated metal is also frequently found in the recesses at bell-and-spigot joints. Even if coatings could somehow be applied in these recesses, bonding to the substrate will be prevented as debris accumulates here and cannot be removed in any practical way. Polyurethane and particularly polyurea linings are very sensitive to the quality of surface preparation and presence of moisture. In a field demonstration sponsored by the EPA, the collapse of a polyurea lining was discovered during flow testing, which provided further confirmation of problems previously identified in Project 4095, and prompted a reformulation by the manufacturer (Matthews, et al, 2011). Structural Lining Materials The aging processes for HDPE, PVC, and other pipeline materials are discussed in Chapter 3. Where systems are conservatively designed and well constructed, they would be expected to last at least 50 years, with occasional repairs. While cured-in-place pipe lining systems have been around for many decades, the vast majority are for non-pressure pipe applications. The long-term integrity of CIPP reinforced with fiberglass and other fiber reinforcement is a recommended subject for future research. According to most manufacturers, these systems are intended for 50-year lives. Approximately 2.5 million feet water mains have been rehabilitated with reinforced CIPP since 2000, reportedly without any failures.

178 Answers to Challenging Infrastructure Management Questions Semi-Structural Systems The life expectancy of a semi-structural system relies to a great extent on the ability of the host pipe to continue to function without splitting or fracturing. While predicting which pipes might fail is difficult, the corrosion pit model discussed in Chapter 3 provides some insight, as shown in Figure 6.8. In this example, the model predicts that an 8 mm pit in a 75- year-old pipe should grow to just over 9 mm in the next 50 years. If this pipe has only moderate pitting and a record of relatively good performance, the risk of facturing may then be judged to be low. Adapted from Rajani et al. 2011 Figure 6.8. Using the pit-growth model to forecast future deterioration. WHAT FACTORS ARE HINDERING GREATER USE OF REHAB FOR WATER MAINS? Spray-on lining is the most common method of water main rehabilitation in the United States, but compared to the UK, the level of activity in the US is low. The reasons are the younger age of US infrastructure, the greater fragmentation of the US market, the greater diversity of regulators, and the less congested streets. These factors allow deferral of work, favor a traditional approach, and make the cost of open-trench replacement appear more competitive. The fact that open-trench replacement produces a new pipeline with well-defined expectations, whereas spray-on lining achieves a less certain life extension, no doubt limits the current acceptance. Several WaterRF projects have focused on improving the efficiency and economics of water main rehabilitation, including: Demonstrating same-day return to service for polymer-lined mains (avoiding the cost of bypass piping) Demonstrating the use of pre-sanitized pipe in pipe bursting projects (also avoiding the need for bypass piping) Demonstrating the use of keyhole methods for reconnecting service laterals, after a pipe bursting project

Chapter 6: Pipeline Renewal Methods 179 Documenting other concepts and techniques for non-dig reconnections of service laterals The full potential of rehabilitation may never be realized until these ideas are broadly used and perfected through practice, but because the US water industry is so fragmented, the advancement of these concepts is an uphill battle with only modest potential rewards. Entrepreneurs are reluctant to invest in new technology, gauging the market as limited. The market stays small, partly because the technologies are not optimized. AFTER REHABBING A PIPE, HOW DO I RECONNECT SERVICES WITHOUT DIGGING HOLES UP AND DOWN THE STREET? If using a non-structural lining method (CML or spray-applied polymer), the reconnection of services is not a problem. With CML, a short blast of compressed air unplugs the lateral before the lining sets up. With polymer linings, the lateral is seldom plugged to begin with, so no added efforts are needed. This is a prime advantage of spray-applied linings over other methods. With structural and semi-structural methods involving linings that are not spray-applied, re-establishing and connecting the laterals is a much more important issue and significant reductions in the cost of water main rehabilitation could be achieved if methods are developed to reconnect services without excavating a large hole at each one. Figure 6.9. Keyhole methods. Project #2872, No-Dig and Low-Dig Service Connections Following Water Main Rehabilitation (Ellison, et al., 2006) demonstrated the use of longhandled tools (at left) for reconnecting services within several small, vacuum-excavated holes (at right). This work followed a pipe bursting replacement of a main, performed by the utility s own crews. Three challenges are encountered in reconnecting services in a no-dig manner: (1) finding the lateral, (2) reestablishing the lateral opening, and (3) positively connecting the lateral to the liner or carrier pipe. The extension or adaptation of various existing technologies enables each of these problems to be effectively solved in most cases. Several good concepts for service reconnections exist but investment in their development is hampered because the perceived size of the rehabilitation market is not yet large enough. Ironically, only by bringing such innovations

180 Answers to Challenging Infrastructure Management Questions to the market will the desire for water main rehabilitation grow significantly. Because of this economics dilemma, an important continuing role exists for the Foundation and similar organizations in funding research and communicating results. In the last decade, progress has been made in service reconnectoins robotic tools used by one company have been successful in reconnecting about half of the services in most mains but more work is needed. It is believed that significant near-term progress can be achieved with other moderate investments. Practical applications of keyhole methods (Figure 6.9), in particular, could be forthcoming with such assistance, especially if utilities would bid large projects that allowed these techniques. CAN I LINE THROUGH VALVES AND FITTINGS? The general answer is no. While the ability to line through fittings varies with the degree of the bend, the size of the pipe, and the rehab method that is employed, usually an excavation will be needed at most fittings. Similarly, excavations will be needed at nearly all valves. Often these excavations will also serve as access holes for the lining work. HOW DO I KEEP CUSTOMERS SUPPLIED DURING A REHAB PROJECT? For most rehabilitation techniques, keeping customers supplied is a consideration. This is typically done using temporary pipe laid in gutters on each side of the street. The temporary pipes are generally 2 to 4 inches in diameter and are supplied from a fire hydrant, but can range up to 12-inches (Figure 6.10). Sometimes a tap or connection to an adjacent main is required. Source: Photo courtesy of Michael Grahek Figure 6.10. Bypass piping Short pieces of hose are used to connect this bypass or sideline pipe to the service pipes at the meter. To make the connection at the meter, the meter must be removed, and is either reinstalled laying on the ground, or is simply removed completely, and the customer s

Chapter 6: Pipeline Renewal Methods 181 water use is estimated for the duration of the project. 93 Where the bypass pipe crosses driveways, cold asphalt mix is mounded over the pipe to permit vehicle passage or preformed rubber ramps are used. Rehabilitation contractors often have crews that specialize in installation and removal of such systems, and the work can be quite a project in itself. Among the details to be addressed: Assuring adequate disinfection, bacterial testing, and flushing. Sizing the pipe to serve large customers or to replace large mains. Where bypass piping exceeds 4 inches in diameter, trenching is required where the pipe crosses driveways and alleys. Assuring customers are supplied from the correct gradient zone, where two mains exist in the street. Assuring that an adequate number of hydrants remain in service, and that they are adequately supplied. (Hydrants that are inoperable must also be properly identified.) Avoiding undue hazards to vehicles and pedestrians from the pipes and hoses laid on the ground. Keeping the water from getting too hot in the summer (customers complain), or too cold in the winter (pipes freeze). Because the work involved in constructing, maintaining, and removing bypass systems is considerable, substantial savings would result if bypassing could be avoided. One alternative is to simply park a water truck on the street, and let residents draw from it for the duration of the work, but more realistically, you might look for a method that permits a main to be returned to service after only a few hours of work. Various parties have been working on this second alternative for some time. Cleaning, lining, and returning a main to service within a workday is possible from a process standpoint. Those rehabilitation systems which don t require extended cure times are usually capable of achieving this goal, provided that work is well planned. The big hurdle is being able to safely place the main in service, without super chlorination and bacterial testing, and gaining permission to do so. This too appears to be possible, but requires coordination and cooperation between the utility, the rehabilitation contractor, health officials, and customers. 94 In the UK, same-day return to service after lining has become the rule, not the exception, and health officials there are now so confident in the processes, that confirmation bacterial testing is not generally required. 93 Where meters are deeply buried or installed within basements, other connection details are needed. 94 Some of the lining methods are inherently sanitary, and risks should be minimal, provided that strict work procedures are followed. In the UK and in Canada, the ability to line pipe without jeopardizing health has been demonstrated. In the US, bypass piping could be avoided by distributing bottled water to and issuing a boil water advisory until experience and confidence in the process is gained. A US project utilizing same-day return to service was recently completed in Oswego, NY (Folgherait, Rogers, and Kirsch, 2013).

182 Answers to Challenging Infrastructure Management Questions WHAT OTHER TRENCHLESS METHODS CAN BE USED FOR WATER PIPES? Horizontal Directional Drilling (HDD) Used extensively in the telecommunications industry, HDD has also been employed in the water industry for installing pipelines under freeways, rivers, busy intersections and other areas with open-trench excavation is difficult. Entry-to-exit distances of up to one-mile have been successfully achieved. Jack-and-Bore This method has been used for decades to cross beneath railroads, freeways, and other obstructions. It is particularly appropriate for gravity pipe installations, where strict grade control is needed. Pipe Ramming Similar to pile driving, the process is particularly useful for installing casing pipes through gravelly materials. Tunneling/Microtunneling The construction of large-diameter pipelines in dense urban areas often requires tunneling due to utility congestion and traffic issues. Pilot-Tube Microtunneling This technique is a hybrid between HDD and microtunneling, and is useful for short bores of several hundred feet. Piercing Tools/Moles Pneumatic hammering tools are often used to install small diameter pipes under sidewalks, streets and other short-distances. Service Line Pulling or Splitting A cable inserted through an existing service can be used to simultaneously extract the old lateral and install a new lateral. A similar method splits the old lateral, as the new one is pulled into place. SHOULD I CLEAN MY PIPES? HOW SHOULD I CLEAN MY PIPES? This question is largely addressed in Chapter 4 (Water Quality). Project 2688 (Ellison, 2002) investigated common pipe cleaning techniques (conventional flushing, unidirectional flushing, air scouring, swabbing, pigging, and mechanical cleaning) and found that each can be

Chapter 6: Pipeline Renewal Methods 183 useful for addressing specific conditions. Flushing is the most useful, addressing a host of problems very economically. At the other end of the scale, in-situ cleaning and lining is an important technique for dealing with the unlined iron pipe problem. The need and efficacy of the various methods should be based on physical data (pressure, flows, turbidity, HPC, ph, and disinfectant residual) gathered at regular intervals from key locations throughout the distribution system. Should Tuberculation be Removed? Removing tuberculation sounds like a good idea. Tuberculation reduces fire flow capacity and increases pumping costs. Tuberculation forms in the direction of water flow, and provides recesses where sediment is deposited, water stagnates, and coliform regrowth can occur. If flow in the pipe is reversed, or if the pipe is disturbed, a large volume of sediment can be released into the water causing severe water discoloration. Such problems can occur when hydrants are opened, construction is taking place, when valves in the system are operated, or even when heavy traffic occurs in the street above. The sediment accumulation in unlined pipes is dramatically shown in Figure 6.11, which shows a cleaning pig emerging from a fire hydrant connected to an old cast iron main. However, tuberculation also generally slows the corrosion process, protecting the pipe underneath. Therefore, removing the tuberculation can accelerate corrosion and lead to an early failure, if the pipe is not subsequently lined. In general, unless the pipe is to be lined or otherwise renewed within a few years, aggressive cleaning should not be used. Aggressive cleaning of unlined mains can result in more rather than fewer complaints. Source: Photo: Pipeline Pigging Products, Inc. Figure 6.11. Pipe cleaning pig emerging from a fire hydrant. The sediment accumulation that can occur in unlined cast iron mains is well illustrated by this picture.

184 Answers to Challenging Infrastructure Management Questions HOW DO I GET A PIPELINE RENEWAL PROJECT STARTED? If you have people who know how to manage pipeline projects, while maintaining operations, and keeping customers supplied with water, you already have most of the requisite skills for managing a pipeline rehabilitation project. With a little homework and help, you ll be well on your way. Specifically, you ll need: Drawings. You need to define the project limits, and indicate what is to be rehabilitated and what is to be replaced. Economy of scale applies, so make the project as large as you can manage. Although pipeline rehabilitation contractors frequently bid jobs where information is sketchy, the more detailed the drawings, the lower the risk to all parties, and the better the price. For most types of rehabilitation, the locations and types of fittings, bends, valves and other appurtenances will be important, so dig through those old files. Specifications. Pipe rehabilitation is specialized work, and for the most part, the contractors who work in this field are professionals well versed in the requirements. There are, however, exceptions out there, so you need to have well written specifications, with good general and special condition sections to protect your utility and customers. Among the issues to be addressed in a pipe rehabilitation contract are: o Customer service requirements. The contractor may be working literally in the front yards of your customers. Make sure bidders understand that customers are to be treated courteously, their problems must be resolved rapidly, their claims must be handled fairly, and appropriate notice of service interruptions must be given. o System operation requirements. Who is responsible for opening and closing valves, and whose permission is needed? o Disinfection, bacteriological testing, and flushing requirements. The degree of owner involvement in these activities varies, so let bidders know specifically what their responsibilities are. o Bypass system design and maintenance. If you expect the contractor to respond to a break in the middle of the night, let him know. o Metering. While work is underway, how is customer metering to be handled? o Material requirements. What kinds of fittings, pipes, and other materials do you want? How much is owner-furnished? Will factory inspections be required? o Construction standards. What will be inspected? What are the technical specifications? What tolerances are acceptable? o Traffic control and public safety. What are the standards? What permits are required? o Repaving. Can the contractor simply patch holes, or will an overlay be required? What are the standards? o Schedule of pay items. Adjustments may be needed to accommodate differing field conditions, so you ll want a schedule of unit-price pay items that clearly defines what is included in each.

Chapter 6: Pipeline Renewal Methods 185 If possible, prequalification of contractors is a good idea, using a procedure where the contractors are scored using scored interviews of their references. Construction Management and Inspection You ll want a person assigned to the field who has many talents. Your construction manager should: Know hydraulics and how your system operates. Know your organization and the various responsibilities. Be well trained in customer service. Be skilled at contract administration. Be knowledgeable of the specific inspection requirements for the project. Experience counts, so if you have not tackled such a project before, you may want to look to others for guidance or help. The national and regional AWWA Pipeline Rehabilitation Committees can refer you to contractors, consultants, and owners who are experts in this area and willing to provide assistance, including copies of plans and specifications for similar projects. Other sources of information include fellow utilities, consulting engineers organizations, state environmental departments, and contractor organizations.

CHAPTER 7 MANAGING A WATER MAIN RENEWAL PROGRAM This chapter addresses the most challenging question in infrastructure management; how to obtain and sustain support and funding for a long-term infrastructure renewal program. The ideas offered here are based on successful programs operated in Los Angeles, Denver, Phoenix, and other major cities. This chapter includes ideas for: Building a case for an infrastructure renewal program Determining funding requirements Developing public and political support for the program Finding ways of financing the program Allocating money to obtain the greatest benefits Making the program successful HOW DO I BUILD A CASE FOR A PROACTIVE RENEWAL PROGRAM? The short answer is: Do your homework. Chapter 2 discussed how to analyze the system and determine renewal needs. Chapter 5 discussed methods for assessing the condition of individual assets. To build a good case, you need gather data, evaluate assets, and perform the analyses and confidently present the results. People will ask: What are the costs? What are the benefits? What is the benefit/cost ratio? How does this system compare with others particularly neighboring utilities? Who has similar programs? What kinds of costs have they incurred? What benefits are they seeing? What happens if we do nothing? In building your case, numbers are important, but don t rely on numbers alone. Remember, not everyone is technically oriented and your case needs to appeal to a wide range of people. Develop some good narratives. Describe how the infrastructure affects customer service, businesses, fire protection, and other community services (such as hospitals). What are the risks associated with blowouts, including flooding damage and traffic tie-ups? How is the cost of an emergency repair different from a planned replacement? Don t be afraid to discuss how the pipes affect the safety and acceptability of the water. Make the effort to get illustrations and physical samples. Collect samples of red water and tuberculated and failed pipe. HOW MUCH MONEY WILL I NEED? Forecasting infrastructure renewal needs is not easy, and methods for making this determination are discussed in Chapter 2. Kanew, a WaterRF-developed computer program, is useful in making these calculations. There is no exact answer to this problem, only good (and not-so-good) estimates. If you miss the mark a little, and your program ends up replacing too much or too little pipe, a course correction will be needed sometime later but this should be years later. The next step is to derive a budget, and this is not quite as simple as multiplying your renewal needs by a cost per foot. Things to consider: 187

188 Answers to Challenging Infrastructure Management Questions Get your unit costs, if possible, from real jobs. Contractors will certainly provide you with costs, but their figures tend to be on the optimistic side. Contractorfurnished costs often focus on a single component pipeline rehabilitation, for instance but neglect the costs of related work, such as traffic control, repaving, bypass piping, replacement of valves and other appurtenances, work performed by the owner or other utilities, and the cost of owner-provided materials. The best unit costs come from other owners who have bid recent similar work. Include your engineering, administration, and other soft costs. Any costs that will ultimately be charged to your renewal budget must be considered. Generally, you want to be conservative in all of your estimates it s always easier to explain why you spent too little than spent too much. Determine a realistic program schedule. If your infrastructure has been neglected for decades, you probably can t correct it in just a few years. Look for a renewal level that is affordable to your customers, that is sellable to your Board, and that gets you where you need to be in the long run. As pipe is replaced or renewed, your infrastructure needs should diminish, so a crash program may not be necessary. With a moderate program, you should be able to catch up over time, but do the analysis to make sure. For public agencies in particular, a steady program with constant expenditures is more easily managed than one with large peaks and valleys. Evaluate the benefits. Different levels of investment will produce different-sized benefits. It is useful to show how future failures and related costs will be affected by various renewal rates and the burden that falls on future generations. HOW DO I SELL THE PROGRAM TO MY CUSTOMERS AND THE BOARD? Being good at this task requires political skills that many managers and engineers lack. So, the first thing to consider may be who is the right person to make the pitch. It may be your responsibility, and you may be the most knowledgeable person on this issue, but good analysts don't often make good lobbyists. It simply takes a different set of skills. To sell your program successfully, you ll again need to do some homework. It s not just a matter of putting together a slick presentation. First of all, what is your message? From your perspective, you see the program as providing certain benefits, such as better reliability, fewer crises, and fewer calls on the carpet, but what are the benefits to your stakeholders? Your message needs to address their needs, and you shouldn t just imagine what they are, you should ask them. Use surveys, interviews, focus groups, and one-on-one meetings whatever means are appropriate. Your list of stakeholders should obviously include customers and Board members, but consider also what are the interests of your employees, political leaders, health officials and the media, and how each will view a renewal program. Asking questions is the best way of starting conversations, so be prepared for a dialog. This is one of your best opportunities to educate people about your infrastructure needs. However, be sure to listen first. The infrastructure is your problem and most people will have little interest in it, initially. They d rather talk to you about the cost of water, how it tastes, and service problems they ve experienced. They will only be interested in your infrastructure problem, if they can see how it relates to these other issues.

Chapter 7 Managing a Water Main Renewal Program 189 Obviously, there are strategies for developing and delivering a message that will win support, and this book cannot begin to fill that need. It would be nice to hire a media consultant, but if you are a public agency manager, your chance of doing that may be limited. Instead, you ll have to use whatever resources you have available, including your team of employees. As much as you can, educate, communicate, be creative, and get people excited! A balanced team is needed. This means having expertise from various disciplines and organizations: engineers, operators, managers, accountants, and public outreach. It also means having various personality types the exuberant, gregarious people, as well as the serious, analytical people. Effective teams often need a balance of each the four personality types, as defined by Myers-Briggs and others. 95 HOW CAN I FUND MY PROGRAM? Just as there are creative ways to sell your program there are creative ways to fund it. It would be nice if the Board allowed you to simply raise your rates to pay for an on-going program, but this isn t always feasible. Renewal programs have been funded through capital improvement bonds, rate surcharges, redevelopment program funds, development fees, and sales/lease back programs. Bonding Many systems have a tradition of pay-as-you-go funding for most of their infrastructure renewal. However, borrowing money through bond issues may be appropriate for this kind of program. The program will benefit consumers for many decades, so it makes sense that future consumers might pay some of the costs. This rationale is particularly appropriate if the program is one where intensive investment in the near-term will result in lower costs in the long-term. A renewal program also raises the asset value of the utility, so from a financial standpoint it makes sense that a portion be covered by debt. Rate Surcharges If large expenditures will be relatively short-lived, perhaps a rate surcharge is appropriate. A rate surcharge is different from a general rate increase in two ways. First, it is earmarked for a specific expenditure. Second, its duration is limited perhaps it lasts for five years. Together these features make a surcharge an easier sale than a base rate increase. The short duration may seem like a drawback, but this isn t necessarily true. Governing boards will frequently renew these surcharges, as long as the utility can demonstrate that the money is being spent as intended, and benefits are being obtained. 96 95 Carl Jung, Katherine Briggs and Isabel Myers developed a system which classified personalities into four quadrants (intuitive, thinking, sensing and feeling) and 16 subcategories, which have been modified by others (e.g., driver, analytical, amiable, expressive). 96 Faced with significant capital needs, the Los Angeles Department of Water and Power enacted a water quality improvement surcharge. The amount of the surcharge was tied to specific expenditures, and if the expenditures didn t occur (e.g., if a project fell behind schedule), the full surcharge was not collected. Every quarter, the utility had to report to its Board what had been expended, what had been accomplished, and what were the estimated expenditures for the next period. The Board would then adjust the surcharge as appropriate. A substantial portion

190 Answers to Challenging Infrastructure Management Questions Redevelopment Programs Neighborhoods targeted for redevelopment usually have old pipes, as well as old buildings; and good arguments can be made for including renewal of publicly owned pipes in any redevelopment programs. First of all, pipe renewal may be needed to meet modern fire flow requirements or to meet the larger demands expected from redevelopment. Also, the success of the redevelopment project will be compromised if poor quality water continues to be delivered to consumers in the area, and if the streets are soon spotted with patches from pipe repair jobs. Developer Funding Most communities have mechanisms by which developers pay for some of the improvements needed to get water to their projects. The same concepts have also been used to tap developer funding for pipe rehabilitation and other infrastructure improvements. For instance, one city imposed general fire protection levies on all developments to fund the addition of hydrants and the relining of tuberculated pipe. Developers have also been asked to fund specific pipeline improvements targeted to improve delivery of water to their developments. Such improvements have been required as conditions of the entitlement process, or as conditions of the connection agreement. 97 Public/Private Partnerships At least one rehabilitation contractor offered sales/lease-back financing. The contractor performs the pipe rehabilitation using financing from its own lenders. Upon completion, the rehabilitated pipe is then owned by the contractor, and leased back to the utility. After a certain number of payments (covering 15 years, perhaps) ownership of the pipe reverts to the utility. The advantages of this arrangement can be several. First, the financing is obtained offbalance sheet, meaning that the lease obligation may not be considered a liability, and may not affect the utility s debt ratios. 98 Second, such financing may be simpler for the utility than the issuance of bonds. Third, because the contractor owns the rehabilitated pipes, the contractor may also be obligated to maintain them (depending on the contract), which essentially provides a long-term warranty of the work. Government Grants and Loans These may include revolving loan programs, rural water grants, and specialty grant programs. The State of Arizona established a Water Infrastructure Financing Authority, which provides infrastructure loans to public utilities. of this surcharge was used to pay for pipe rehabilitation, since it improved the quality of water delivered to the older portions of the city. 97 In order for a utility to certify a desired fire flow for a new building, for instance, the cleaning and lining of an old main might be needed. By agreeing to pay for the pipe rehabilitation, the developer may be able to save money on the building s fire protection requirements. 98 These assumptions need to be verified by the utility s accountants.

Chapter 7 Managing a Water Main Renewal Program 191 Long-Term Maintenance and Warranty Programs These are not financing techniques, but can be helpful when convincing governing boards and the general public to invest in old pipes. If the technology is relatively new, and the pipes are 80 years old, how can you be sure it will work? The risk is significantly reduced if the contractor provides a long-term warranty. One contractor offered a 15-year warranty, backed by a nationally recognized insurance company, and on a variety of public works contracts, more and more owners are asking for similar extended warranties in their specifications. Warranties have been backed by performance bonds, escrow accounts, or long-term maintenance contracts. 99 ONCE I GET THE MONEY, WHAT S THE BEST WAY TO SPEND IT? The best allocation of your program budget will depend on technical, political, and managerial considerations: Technical considerations, such as hydraulics, water quality, and system reliability will determine which pipes go to the top of the list. Unfortunately, if your system is like many, there will be many pipes at the top of the list. Political considerations should never be ignored and a key consideration may be spreading the work around. Even though the bad pipes may be concentrated in the city s center, for instance, it may be prudent to seek out old pipes in all areas of town, so that all customers receive some benefit from the program (and all Board members can claim some involvement). Managerial issues will likely be the deciding factors in determining how to package the work. Chiefly: o Project Size. Economy of scale applies to rehabilitation work, and packaging contracts into an economical size can save considerable money. For cement mortar lining projects, for instance, many contractors are geared for projects between 20,000 feet and 50,000 feet of small main, performed over the course of 6 to 10 months. Projects smaller than this will entail some kind of premium. Too often utilities package the work to conform to some artificial constraint, without finding out what is the most efficient size from the contractor s perspective. o Coordination with other public works projects. Justly or unjustly, few things will draw more criticism than the apparent poor coordination of public works projects, so make sure your pipes are fixed just before the street is repaved. With a reliable source of funding, renewal programs can be planned with 5-year horizons or more, making it possible to forecast with good precision which streets will be tackled when. o Project Management Issues. Although the contractor may prefer to tackle the entire district in one large sweep, there are limits to how large a project the utility can manage. The limits are determined by such things as what personnel are available to support and oversee the contract work and how many of the large mains can be removed from service at any given time. 99 A bond-backed warranty greater than 3 years is difficult for most contractors to obtain, but for a very large infrastructure program, solutions to this problem are possible.

192 Answers to Challenging Infrastructure Management Questions o Community impacts. The renewal program manager needs to be sensitive to how her program and other public works projects may affect each neighborhood. Is it better to make a full court press, and address all the infrastructure needs of the neighborhood at once, or do one street this year, and the adjacent street next year? The answer will depend on the personality of the community, the nature of the work, and what other projects are occurring around the same time. As much as feasible, the program manager needs to seek out other utilities and departments, to coordinate projects. WHAT ELSE IS IMPORTANT IN DELIVERING A FIRST-RATE PROGRAM? Customer-First Attitude An infrastructure renewal project is intended to enhance customer service, by improving water quality and reliability. So if, at the end of the project, the customer is left with a negative attitude toward the utility, the project will have been a failure. It s hard to deliver pipeline renewal projects that make customers happy. By their very nature, such projects are messy and intrusive. Work takes place literally in the their front yards, obstructing access to homes, scattering dirt about, disrupting water service, and leaving pavement spotted with patches. And this is when the work goes well. When there are problems, any number of horror stories can be told. To begin to win over customers, three rules need to be followed: (1) communications, (2) communications, and (3) communications. Successful programs excel in this with letters sent to each house, before the first mark is ever drawn on the pavement, followed by other letters when work starts on each street. The letters explain why the project is occurring, how it will be accomplished, what to expect, and how long it will take. Not only do these letters include the names and phone numbers of pertinent contacts, but they also contain business cards (or refrigerator magnets), for easy referral. At each critical step in the process, particularly when service is to be interrupted, a notice is hung on the door a day before, and a friendly knock and verbal request must precede the actual turning of valves and never, ever shut off service when the meter is spinning, or an irate, wet and soapy customer may soon appear! Unfortunately, during a pipeline renewal project, customers will inevitably experience some problems: Restricted access to their homes, businesses, and schools Ruined laundry (when slugs of dirty water are released simply by operating valves) Plumbing, sprinkler, and appliance problems (from specks of rust and sediment that clogs valves and filters) Damage to vehicles (particularly tire damage caused by parking on top of bypass piping connections) Trampled flowers and other landscaping damage Leaks in the customer plumbing systems (caused by decades of corrosion, but triggered by the construction activities)

Chapter 7 Managing a Water Main Renewal Program 193 It s tempting to dismiss such problems as either trivial or the fault of the customers themselves. But the point to remember is that the customer did not ask for the project. Your project is an intrusion on their lives. (Never forget who pays whose salary.) Don t shy away from hearing customer concerns. Experience has shown that few people will abuse the opportunity. During the height of a million-feet-per-year rehab program, one program manager included his phone number in letters to every affected customer. Rarely did he receive phone calls, but when the phone did ring, it generally concerned something that was easily fixed. It is generally better to solve these minor issues than to argue about them. If the rehabilitation contractors clearly understand that they must promptly solve these customer problems, the good contractors will include allowances in their bids. In any event, to assure satisfactory customer service, you ll want to monitor how the contractor deals with such customer problems and claims. It s also a good idea to have a thorough video or photo survey of the project area taken in advance of work. This protects customers, the contractor, and the utility. Hold the Contractor Responsible Experienced pipe rehabilitation contractors understand how to address customer claims. If they know that this is their responsibility, they will handle it. The same is also true of practically every other aspect of a water distribution system project. The good contractors know (or can learn) how to design and construct bypass systems, operate valves, chlorinate and sample water, and generally maintain a safe, relatively continuous flow of water. Contractor personnel can also be trained to accurately read and record meter readings. They can respond to line breaks and hydrant knock offs, even in the middle of the night. Getting contractors to perform such tasks is mostly a matter of establishing and clearly communicating the rules. Often utilities undertake to perform these tasks themselves, because they don t wholly trust the contractors. When the utility does step in, coordination problems arise, creating inefficiencies and avenues for claims. Say No to Petty Contractor Claims The conditions that confront a rehabilitation contractor are very unpredictable. Pavement in some older streets may range up to 2 feet thick, with multiple layers of asphalt, concrete, brick and cobbles. There s also no telling how difficult the interferences with other utilities will be, until the excavation is made. Working on an old piping system has its own set of risks. Things break. Sizes are unpredictable, so fittings sometimes aren t compatible. The soil is also unpredictable, since you have no idea what fill might have been used. Other conditions such as traffic and customer demands will also interfere with the work. Any of these unpredictable items could give rise to contractor claims that conditions are more difficult than expected. A common strategy against such claims is to do a lot of research, take a lot of field measurements, pothole throughout the area, and add this information to the specifications and drawings. This is normally good practice, but the approach can backfire. First, if the bid documents become voluminous and confusing, bidders raise their prices for fear that they will miss something. Secondly, by representing that a certain condition exists, you are providing the basis for a claim or argument wherever a different condition exists.

194 Answers to Challenging Infrastructure Management Questions An alternate approach is the law of averages. This law is based on the fact that for every condition that is more difficult than average, there is a condition that is easier than average. You won t hear about the easier conditions, because the contractor will never offer you a credit for work that is easier than normal, but they occur. So if your project is large and involves many items of work, the more difficult conditions should roughly be balanced out by the less difficult conditions. The law of averages works even better if your program is large, and the same contractors work on several different projects, the tougher projects will be balanced by the easier projects, and overall, the contractors make a fair profit. For the law of averages to work, expectations need to be properly calibrated. You want the bidders to understand that you will not pay claims for unanticipated conditions that are common in old water systems. If they understand this, they will base their estimates on average rather than ideal conditions. One way to communicate this is to define expected conditions in a manner similar to a geotechnical baseline report, including a range of pavement, utility and soil conditions that may be encountered in the course of the work. Consistency is important. If you view the claims of each contractor in the same light, the contractors will appreciate the level playing field, and should bid accordingly. Most of them will appreciate not having to play the claims game to get a fair profit. 100 Make Provisions for the Genuine Extra Work That Will Occur Because rehabilitating old systems is unpredictable, a number of conditions will occur which will require significant changes in plan. An old valve may break, necessitating its replacement. An old pipe may start to leak, requiring that a section be replaced. An unrecorded fitting may block the passage of cleaning and lining equipment through the pipe. When these events occur, the contractor is forced to stop work, investigate the problem, procure material and equipment, and probably dig a rather expensive hole to remedy the problem. As work progresses, you may also discover additional work that needs to be done. Perhaps some items need to be replaced, such as lead services and malfunctioning hydrants and meters. The number of these items can vary considerably from project to project, and it is not reasonable for the contractor to include allowances for these problems in his bid. However, this doesn t mean that you shouldn t. When bidding a project, why not ask for several extra hydrant renewals, a dozen extra meter replacements, a thousand square feet of additional paving, and perhaps ten service lateral renewals. Depending on the conditions encountered in the field (and the price offered by the contractor) you can choose to use these items or not. To fix the leaking pipe, replace the broken valve, or remove the unknown obstruction, an easy solution is to include a bid item for additional access holes. An additional access hole is defined to include the work not only to excavate and backfill an excavation (typically 4 feet by 6 feet), but to remove and replace a nipple or valve (with the utility providing the valve). If the pay items are well defined and understood by both parties, you might enjoy considerable flexibility in responding not only to the different conditions in the field, but also to changes in priorities. Should you decide, for example, that Maple Street is now a high priority (due to flow problems, street reconstruction, or customer complaints), you can add the street to an existing contract. Few contractors turn away such work, and it saves the utility the time and 100 Disposition of contractor claims, of course, must comply with applicable state laws and local ordinances.

Chapter 7 Managing a Water Main Renewal Program 195 expense of having to advertise a separate project one that would likely be small and relatively expensive. 101 Trust, But Verify Use partnering, value engineering, and alternate conflict resolution techniques, where possible. The benefits of these methods are indisputable. But don t neglect to measure contractor performance, check the quality of the work, and insist that it meet specifications. Make sure customer problems are addressed in a timely manner. With your control over progress payments, you have considerable leverage in getting things done correctly. Also, give the contractor a report card. Giving the contractor a monthly report card, with grades for such things as site cleanliness, customer responsiveness, timeliness, and quality of work, lets the contractor know what your expectations are, and areas where improvements are needed. And if the contractor takes no action to improve poor grades, the report cards become documentation that can be used to deny the contractor future work, (or in extreme cases, terminate the contract). If you use report cards, your specifications should clearly state, what is being graded, and why. 102 Ask Your Customers for a Report Card If you re willing to grade your contractors, you should be willing to be graded by your customers. Figure 7.1 provides an example. Asking your customers for a report card at the end of the project is important for several reasons: Comments by customers may give you ideas for how to improve the program Customers will report problems of which you re unaware often problems that can be easily solved The report card gives you a way of measuring the effectiveness of the program, the contractor, and your field representative By asking for a grade, you are telling the customer that you care The report card can be used as a subtle final explanation as to why you tore up their street and intruded upon their lives Don t be surprised if few customers return the report cards. Frankly, most people won t care that much that you were there, and won t take even a minute to fill in a survey card and drop it in the mail. A low response rate should be considered good news. Don t be afraid of the responses you ll receive. Certainly, some people will use survey cards to vent their anger, but on the whole comments will likely be positive, and grades will be fair to good. Most customers will perceive the improvement in water quality, and appreciate the 101 The Los Angeles Department of Water and Power took this concept further, having developed a price-and-time contract for pipe cleaning and lining work that can be used anywhere in the City. Because these services are applied to small projects, the City pays approximately 10 to 15 percent more than for their typical cleaning and lining contracts. 102 A frequent complaint in the public sector is the difficulty in barring unqualified contractors from receiving contract awards. Because pipe rehabilitation work is highly specialized, you re likely to see the same group of contractors again, so a report card system can be effective in this regard. Like the grades you receive in school, the contractor s grades can be somewhat subjective, but should be based on evidence and examples.

196 Answers to Challenging Infrastructure Management Questions efforts by the utility to improve the system. They will recognize your efforts to manage the work with minimal traffic problems and service interruptions. Source: Los Angeles Department of Water and Power Figure 7.1. Post project customer survey card Better still, a few customers will provide you with glowing reviews and comments. These report cards need to be copied and saved they are important tools in celebrating your successes. Celebrate Successes Pipe rehabilitation work does not excite many people. In fact, it is among the least exciting of projects. However, it s important work work that preserves the infrastructure, saves money, increases reliability, and improves the quality of the water delivered. If your program is running smoothly, few people will notice. But you can bet that they ll take note when something goes wrong. So it s up to you to make your successes known. Few of us are comfortable in tooting our own horns, but in a political environment, this has to be done. It helps keep the money flowing and the program alive. So, let managers, board members, customers, and the media periodically know what you re doing, why it s being done, and what great performers you have on your team! Track your progress, using colorful maps and charts. Take the time to write reports. And when customers sing your praises, which they will do, get it in writing (so it can be shared). Most of all, share your successes with your employees and contractors, those who work hard to make the program a success this rewards good performance, boosts morale, and keeps the energy level high.

APPENDIX A - COMMON WATER SYSTEM CORROSION PROCESSES A short review of common corrosion processes in water systems is provided. GALVANIC (OR BIMETALLIC) CORROSION Galvanic corrosion is the electrochemical process involving a cathode, anode, electrolyte, and current path in essence, a battery (Figure A.1). All four elements must be present for corrosion to occur. The anode is where oxidation occurs. The cathode is where reduction occurs. Sometimes the anode and cathode are different metals that are connected electrically together, but they can also be different areas on the same pipe. The electrolyte in this process is the water inside the pipe or the moist soil surrounding the pipe. The term galvanic corrosion usually refers to the condition where two different metals are involved, whereas electrochemical corrosion is the more generic term. Galvanic Series The potential for corrosion is determined to a large extent by the two metals relative position in the galvanic series, a version of which is found in Appendix B. The greater the difference between the metals, the greater the corrosion driving force. Materials that are higher on the list (more negative) become anodes with respect to materials that are lower. Cathode and Anode Size CORROSION ANODE ELECTRONS CURRENT GALVANIC CORROSION Figure A.1 Elements of a Battery CATHODE + ELECTROLYTE How quickly something corrodes can depend on the relative sizes of the anode and cathode. For instance, a brass corporation stop and copper service line attached to a cast iron main will act like cathodes, but because the bare main is relatively massive compared to the valve and service line, corrosion of the anode (the main) will proceed somewhat slowly. On the other hand, a small steel nipple placed within a copper plumbing system may start to leak from corrosion within a few months (as many unfortunate homeowners have discovered). 197

198 Answers to Challenging Infrastructure Management Questions Corrosion Pitting and Rust Holes Metallic corrosion, particularly of iron and steel, can be highly localized, resulting in small pits and rust holes while surrounding metal is unaffected. This occurs for several reasons, but a common cause is a small holiday or pinhole in a coating system. Only a small defect in the coating is needed for corrosion to start. Since rust takes several times more space than the uncorroded metal, as it expands it lifts the coating, exposing more metal and leading to more rust. In this way, a small defect in the coating can eventually lead to a hole right through a pipe. Pitting may also occur due to local environmental conditions ( hot soil ) or some kind of metallurgical anomaly. Highly localized failures are the reason for much of the pipe replacement that occurs. To eliminate perhaps two percent of a pipeline that is corroded, it is not uncommon to replace and abandon the other 98 percent of the pipeline that is still in relatively good condition. Pipe good as the day it was installed, can stretch for thousands of feet on both sides of a badly corroded section. Because corrosion is seldom uniform, it is generally not cost effective to increase the wall thickness of a pipe, to provide a corrosion allowance. Most of this extra metal would never be used. Good linings, coatings, and other protection measures are generally much more economical than buying thicker pipe. Cathodic Protection By reversing the flow of electrical current, an anode can be made into a cathode. This is the idea behind the use of cathodic protection. Making the whole piping system into a cathode protects it. There are two basic types of cathodic protection systems: sacrificial and impressed current. In a sacrificial system, a magnesium or zinc anode is buried in the ground near the pipe, and connected by a bonding wire to it. As the anode corrodes, an electrical current travels from the anode though the soil to the pipe and then returns through the wire. Periodically (perhaps every 20 years) the anode becomes depleted and must be replaced. Impressed current systems are used where the current requirements are larger (due to a large pipe, or poor pipe coating). Impressed current systems apply a direct current to a buried anode, driving the current through the soil to the pipe. An AC/DC rectifier, plugged into the electric utility generally supplies the current. Deep-well anodes are often used, particularly for retrofits, to distribute current over large areas, and avoid electrolytic corrosion of other utilities. In other cases, a continuous wire or ribbon anode may be buried alongside the pipe in the same trench. Such an anode is intended to provide a small uniform current all along the pipe. Galvanic ribbon anodes are also sometimes used to distribute CP current. Passivation Corrosion will be arrested when certain protective films or layers develop on the surface of the metal. Sometimes the layer is provided by the oxidation products themselves, as is the case with copper, aluminum, and stainless steel. An important passivation process occurs when iron or steel is embedded in good quality Portland cement mortar or concrete. The high ph environment produced by the cement can

Appendix A Common Water System Corrosion Processes 199 protect the iron and steel from corrosion for many years. 103 Calcium carbonate and other mineral deposits on the insides of pipes can also inhibit corrosion of the metal. 104 Stray-Current Corrosion This is also called electrolytic corrosion, and occurs where a pipe is in the path of direct current passing through the soil. Since the metal pipe provides less electrical resistance than the surrounding soil, some of the current will travel on the pipe. Localized corrosion occurs where the current leaves the pipe within a concentrated area. The two most common sources of DC ground currents are impressed cathodic protection systems and electrical transit systems. Less common sources are welding operations, DC powered cranes, and DC electrical transmission. Frequently ignored and not that well understood is electrolytic corrosion that arises from the practice of using water pipe as part of the electric grounding system for buildings. A WaterRF-funded study (Duranceau, Schiff, and Bell 1996) found that such corrosion does occur, although it is not as pronounced as with DC circuits. The study also found metal ions can be released in the water, degrading water quality, where an electrical insulator interrupts the flow of electricity and forces the electric current into the water column. This occurs, for instance, where a copper service line connects to an asbestos cement main. 105 Leaching Leaching is the dissolving of a constituent out of a solid. Several leaching phenomena are noteworthy in the context of water infrastructure: Graphitization is an electrochemical process whereby iron (the anode) is corroded and leached from cast iron or ductile iron, leaving behind graphite carbon (the cathode). Ultimately, a shell of mostly graphite will remain, with very little strength. Dezincification refers to the leaching of zinc from various brass alloys. This is a particular problem in many western states, due to the character of Colorado River water. Lime leaching from asbestos-cement, concrete, and cement mortar linings and coatings. Where water is low in dissolved minerals, the leaching of lime from cementitious materials occurs. This can result in significant weakening of the pipe, particularly AC pipe. It can also cause unacceptable elevation of the ph in the water. For this reason, pipe that is cement mortar lined in the factory also sometimes receives a seal coat of asphalt. ph problems are most pronounced with pipe that is lined in place, because richer mortar mixes are used without an asphalt seal coat. Problems are most prevalent in portions of the system where water stagnates, such as in dead ends (Douglas and Merrill 1991). 103 This subject is discussed in more detail later in Chapter 3. 104 The effectiveness of these deposits in stopping corrosion is discussed in Chapter 4, under the topic of aggressive water. 105 The most significant problem with using piping for electrical grounding is the electrical shock hazard it poses to water service workers. Shock incidents occur frequently in the industry, some of which are quite serious.

200 Answers to Challenging Infrastructure Management Questions Lead/Copper Leaching. The leaching of lead and copper from various components of the distribution and plumbing systems is an important health issue in the water industry. Sulfate Attack of Concrete Where sulfate is present in concentrations exceeding 1000 ppm, concrete products may be subject to softening, expansion and degradation. The concern is acute, when sulfate exceeds 2000 ppm. Type II cement is generally recommended for 1000-ppm concentrations. Type V cement is recommended for 2000-ppm concentrations. Softening problems with buried or submerged concrete pipe due to sulfate attack are rare, due to the quality of concrete used (Benedict 1985). Alkali-Silica Reaction As discussed in Chapter 3, alkali-silica reaction (ASR) is a chemical reaction that occurs at the surface of certain types of aggregates (non-crystalline silica), in reaction to the high alkalinity of the concrete. The reaction produces an expansive gel that cracks the concrete. Severe distress to the concrete may result. Tuberculation Tuberculation is an encrustation of corrosion products and mineral deposits that forms on the inside of pipe. It severely affects the hydraulic capacity of the pipe, but also impacts water quality. Tuberculation reduces fire flow capacity, increases pumping costs, and leads to chlorine depletion, water coloration, and taste and odor problems. Tuberculation is most pronounced in unlined cast iron pipes, but it is also found in unlined steel and other types of metallic pipe. The build-up in smaller pipes tends to be greater than in larger pipes and is definitely more significant. 106 The effect on a 4-inch pipe that is already undersized by modern fire flow standards can be huge. Generally, the encrustation will serve to slow the corrosion process, protecting the pipe underneath. The rate of corrosion depends on the rate at which oxygen is transported to the pipe wall. Where cast iron or ductile iron pipe is used, graphite in the corrosion byproducts tends to add strength to the scale and provides a barrier against further corrosion. The mineral, Siderite (FeCo 3 ), in particular, is believed to provide tight scales that restrict oxygen diffusion. A high buffer capacity in the water, as discussed in this report, is believed to encourage Siderite formation, thereby slowing the corrosion of the pipe. 106 The larger build-up on small pipes can be explained by geometric relationships as well as lower average flows.

APPENDIX B - TYPICAL GALVANIC SERIES 107 Metal Volts 108 Commercially Pure Magnesium -1.75 Magnesium Alloy (6% Al, 3% Zn, 0.15% Mn) -1.60 Zinc -1.10 Aluminum Alloy (5% Zinc) -1.05 Commercially Pure Aluminum -0.80 Mild Steel (clean and shiny) -0.50 to -0.80 Mild Steel (rusted) -020 to -0.50 Cast Iron (non-graphitized) -0.50 Lead -0.50 Mild Steel in Concrete -0.20 Copper, Brass, Bronze -0.20 High Silicon Cast Iron -0.20 Carbon, Graphite, Coke +0.30 107 Helgeson, 1985. 108 Cu-CuSO 4 reference 201

APPENDIX C RISK MANAGEMENT TOOLS USED BY WSSC AND SPU Washington Suburban Sanitary Commission (WSSC) WSSC calculates a risk score by assigning weighted values to various asset attributes (see table below) to determine Consequence of Failure scores. The product of these COF scores, along with probability of failure (POF) and a mitigation factor results in an overall risk assessment. Consequence Category Low Impacts High Impacts Social/community/organizational Loss of service impacts (flow and pressure) Reduce fire flow; redundant Can be down no more than 1 hour Public health and safety No impact to minor injury Many deaths, widespread Credibility No media or no consequence Economic / Financial Cost of Failure 0-$100,000 >$2M Operational Impacts Low cost and low operational impact Environmental / Regulatory Unregulated discharges Short duration, small quantity, on-site, no complaints sickness Political opposition; national adverse media Likely trigger rate increase; staff changes Sustained, large quantity, off-site, many complaints 203

204 Answers to Challenging Infrastructure Management Questions Seattle Public Utilities (SPU) SPU has developed a sophisticated scoring system, which is well described in various pages on their intranet.

Appendix C Risk Management Tools Used By WSSC and SPU 205

206 Answers to Challenging Infrastructure Management Questions

Appendix C Risk Management Tools Used By WSSC and SPU 207

208 Answers to Challenging Infrastructure Management Questions

Appendix C Risk Management Tools Used By WSSC and SPU 209

210 Answers to Challenging Infrastructure Management Questions

Appendix C Risk Management Tools Used By WSSC and SPU 211

REFERENCES Abernathy, Robert B. 2006. The New Weibull Handbook, 5th Edition. Published by the author. Alben, Katherine, Auguste Bruchet, and Eugene Shpirt. 1985. Leachate From Organic Coating Materials Used in Potable Water Distribution Systems. AWWARF Project 105. Denver, CO. American Water Works Association. 2011. Manual M48 - Internal Corrosion Control in Water Distribution Systems. AWWA. Denver, CO. American Water Works Service Company. 2001. Deteriorating Buried Infrastructure Management Challenges and Strategies. USEPA. Ancel, Susan, Dave DiSera, Nancy Lerner, and Mary Ann Stewart. 2006. Building a Business Case for Geospatial Information Technology: A Practitioner's Guide to Financial and Strategic Analysis. AWWARF Project 3051. Denver, CO. Atassi Amrou, Marc Edwards, Jeffrey Parks, and Anusha Kashyap. 2009. Impact of Phosphate Corrosion Inhibitors on Cement-Based Pipes and Linings. AWWARF Project 4033. AWWA Research Foundation and DVGW Technologiezentrum Wasser, Karlsruhe, Germany. 2004. Internal Corrosion of Water Distribution Systems, 2nd Edition. AWWARF Project 725. Denver, CO. AWWA. 2012. Buried No Longer: Confronting America s Water Infrastructure Challenge. AWWA, Denver, CO. Ballantyne, Donald. 1994. Minimizing Earthquake Damage, a Guide for Water Utilities. American Water Works Association, Denver, CO Bardet, J.P., D. Ballantyne, G.E.C. Bell, A. Donnellan, S. Foster, T.S. Fu, J. List, R.G. Little, T.D. O Rourke, and M.C. Palmer. 2010. Expert Review of Water System Pipeline Breaks in the City of Los Angeles during Summer 2009. LADWP. Los Angeles, CA. Bargmeyer, Alex M., Mark E. Shirtliff, Phillip W. Butterfield, Anne K. Camper, Melinda Friedman, and Glen R. Boyd. 2004. Innovative Biofilm Prevention Strategies. AWWARF Project 2609. Denver, CO. Bargmeyer, Alex M., Mark E. Shirtliff, Phillip W. Butterfield, Melinda Friedman, and Glen R. Boyd. 2004. Verification and Control of Pressure Transients and Intrusion in Distribution Systems. AWWARF Project 2686. Denver, CO. Battelle, TTC, Jason Consultants, Virginia Tech. 2008. White Paper on Rehabilitation of Wastewater Collection and Water Distribution Systems. USEPA. Benedict, R.L. 1985. Corrosion Protection Properties of Concrete Cylinder Pipe. Paper presented at Seminar on Corrosion Control, AWWA Distribution System Symposium. Seattle, WA. Benjamin, M.M., J.F. Ferguson, O. von Franque, G.J. Kirmeyer, P. Leroy, R.J. Oliphant, S.H. Reiber, R.A., Ryder, M.R. Schock, V.L. Snoeyink, H. Sontheimer, R.R. Trussell, E.A. Vik, and I. Wagner. 1996. Internal Corrosion of Water Distribution Systems, 2d Edition. AWWARF. Denver, CO. Benjamin, M., J.P. Crue and S. Reiber. 1998. Natural Organic Matter and Disinfection By- Product Formation. AWWA Research Foundation. Denver, CO. Bhagwan, J.N.. 2011. Compendium of Best Practices in Water Infrastructure Asset Management. WaterRF Project 4111. Denver, CO. 213

214 Answers to Challenging Infrastructure Management Questions Block, J.-C., V. Gauthier, C. Rosin, L. Mathieu, J. M. Portal, P. Chaix, and D. Gatel. 1996. Characterization of the Loose Deposits in Drinking Water Distribution Systems. Proceedings of the AWWA Distribution System Symposium. AWWA. Denver, CO. Boyd, G., M. McFadden, S. Reiber and G. Korshin. 2010. Effect of Changing Disinfectants on Distribution System Lead and Copper, Water Research Foundation, 2010. Denver, CO. Boyd, Glen R., Matthew S. McFadden, Steven H. Reiber, Anne M. Sandvig, Gregory V. Korshin, Richard Giani, and Anatoly I. Frenke. 2010. Effect of Changing Disinfectants on Distribution System Lead and Copper Release. WaterRF Project 3107. Denver, CO. Brothers, K.J.. 1999. Systematic Water Loss Reduction through Technology Applications. Presentation at AWWA Distribution System Symposium. Reno, NV. Brown, R., N. Mctigue, and D. Cornwell. 2012. Evaluation of Lead and Copper Control Strategies OCCT Regulatory Developments. Draft Report to the American Water Works Association. Denver, CO. Burn, Stewart, Paul Davis, Tara Schiller, Bill Tiganis, Grace Tjandraatmadja, Mark Cardy, Scott Gould, Paul Sadler, and Alan J. Whittle. 2005. Long-Term Performance Prediction for PVC Pipes. AWWARF Project 2879. Denver, CO. Canadian National Research Council. 2007. Infrastructure Assessment. (www.nrccnrc.gc.ca/eng/achievements/highlights/2007/water_2007.html). Carollo Engineers. 2008. Evaluating the Compatibility of Chemical Disinfectants with Plastic Pipe Materials Used for Potable Water Distribution. Technical Memorandum. Carollo Engineers. Austin, TX. Chapman, D., D. Cheneler, N. Metje, A. Thomas, and M. Ward. 2010. Smart Sensors for Buried Utility Location and Performance Monitoring. WaterRF Project 3129. Denver, CO. Chastain-Howley, A., G. Kunkel, W. Jernigan, and D. Sayers. 2013. Water loss: The North American dataset. Jour. AWWA, 105(6) 57:60. Chung, S., M. Conrad, and K. Oliphant 2010. Impact of Potable Water Disinfectants on PE Pipe. Jana Laboratories, Aurora, Ontario, Canada. Clement, Jonathan, Michael Hayes, Pankaj Sarin, V.L. Snoeyink, W.M. Kriven, Jack Bebee, Kevin Jim, Michael Beckett, Gregory J. Kirmeyer, and Gregory Pierson. 2003. Development of Red Water Control Strategies. AWWARF Project 368. Denver, CO. Conroy, Paul J., David M. Hughes, and Ivana Wilson. 1995. Demonstration of an Innovative Water Main Rehabilitation Technique: In Situ Epoxy Lining. AWWARF Project 808. Cook, Dominic, Brendan McAndrew, and Gary Shuker. 2009. Large Diameter Trunk Main Failures. AWWARF Project 4076. Denver, CO. Copper Development Association. 2012. 50 year warranty. (www.copper.org/applications/plumbing/.../cu_50yr_warnty_main.ht...cached - Similar). Cromwell, John, Glenn Nestel, and Rick Albani. 2003a. Financial and Economic Optimization of Water Main Replacement Programs. AWWARF Project 462. Denver, CO. Cromwell, John, Haydn Reynolds, and Kevin Young. 2003b. Costs of Infrastructure Failure. AWWARF Project 2607. Denver, CO. Damodaran, Nimmi, Joanna Pratt, John Cromwell, Jeffrey Lazo, Elizabeth David, Robert Raucher, Charles Herrick, Eric Rambo, Arun Deb, and Jerry Snyder. 2005. Customer Acceptance of Water Main Structural Reliability. AWWARF Project 2870. Denver, CO. Daniels, Simon, Mathew Taylor, Andrew Fraser, and Brian Hewitt. 2005. Remote Sensing Methods for Leak Detection in Water Transmission Pipelines. AWWARF Project 2826. Denver, CO.

References 215 Davis, Paul, Stewart Burn, Scott Gould, Mark Cardy, Grace Tjandraatmadja, and Paul Sadler. 2007. Long-Term Performance Prediction for PE Pipes. AWWARF Project 2975. Denver, CO. Deb, Arun K., Frank M. Grablutz, Yakir J. Hasit, and Jerry K. Snyder. 2002. Prioritizing Water Main Replacement and Rehabilitation. AWWARF Project 459. Denver, CO. Deb, Arun K., Jerry K. Snyder, and James J. Chelius, Roy F. Weston, Inc., and D. Kelly O'Day. 1991. Assessment of Existing and Developing Water Main Rehabilitation Practices. AWWARF Project 314. Denver, CO. Deb, Arun K., Jerry K. Snyder, John O. Hammell, Jr., Elizabeth Tyler, Linda Gray, and Ian Warren. 2006. Service Life Analysis of Water Main Epoxy Lining. AWWARF Project 2941. Denver, CO. Deb, Arun K., Kelly A. Momberger, Yakir J. Hasit, and Frank M. Grablutz. 1997. Guidance for Management of Distribution System Operation and Maintenance. AWWARF Project 457. Denver, CO. Deb, Arun K., Raimund K. Herz, Yakir J. Hasit, Frank M. Grablutz. 1997. Quantifying Future Rehabilitation and Replacement Needs of Water Mains. AWWARF Project 265. Denver, CO. Deb, Arun K., Sandra B. McCammon, Jerry Snyder, and Andrea Dietrich. 2010. Impacts of Lining Material on Water Quality. WaterRF Project 4036. Denver, CO. Deb, Arun K., Yakir J. Hasit, and Frank M. Grablutz. 1995. Distribution System Performance Evaluation. AWWARF Project 804. Denver, CO. Deb, Arun K., Yakir J. Hasit, Chris Norris. 1999. Demonstration of Innovative Water Main Renewal Techniques. AWWARF Project 255. Denver, CO. Deb, Arun K., Yakir J. Hasit, Heidi M. Schoser and Jerry K. Snyder. 2002. Decision Support System for Distribution System Piping Renewal. AWWARF Project 2519. Denver, CO. Dietrich, Andrea M., Andrew J. Whelton, and Daniel L. Gallagher. 2010. Chemical Permeation/Desorption in New and Chlorine Aged Polyethylene Pipes. WaterRF Project 4138. Denver, CO. DiGiano, Francis A., Vanessa Speight, and Weidong Zhang. 2004. Disinfectant Decay and Corrosion: Laboratory and Field Studies. AWWARF Project 2649. Denver, CO. Dingus, Michael. 2002. Nondestructive, Noninvasive Assessment of Underground Pipelines. AWWARF Project 355. Denver, CO. District of Columbia Water and Sewer Authority. 2009. Case No. 03-ca001254 B Defendants Reply in Support of Motion to Exclude Testimony, Under Frye v. United States. Douglas, Bruce D. and Douglas T. Merrill. 1991. Control of Water Quality Deterioration Caused by Corrosion Cement-Mortar Pipe Linings. AWWARF Project 415. Denver, CO. Duranceau, Steven J., Melvin J. Schiff and Graham E.C. Bell. 1996. Effects of Electrical Grounding on Pipe Integrity and Shock Hazard. AWWARF Project 913. Denver, CO. Duranceau, Steven J., Dan Townley, and Graham E.C. Bell. 2004. Optimizing Corrosion Control in Water Distribution Systems. AWWARF Project 2648. Denver, CO. Edwards, M., J. F. Ferguson and S.H Reiber. 1994. The Pitting Corrosion of Copper, Journal AWWA. Denver, CO. Edwards, Marc and Steven Reiber. 1997. A General Framework for Corrosion Control. AWWARF. Denver, CO.

216 Answers to Challenging Infrastructure Management Questions Edwards, Marc and Tom Holm. 2001. Role of Phosphate Inhibitors in Mitigating Lead and Copper Corrosion. AWWARF Project 2587. Denver, CO. Edwards, Marc, Paolo Scardina, G.V. Loganathan, Darrell Bosch, and Sharon Dwyer. 2008. Assessment of Non-Uniform Corrosion in Copper Piping. AWWARF Project 3015 Edwards, Marc, Paolo Scardina, Russell Taylor, and Nigel Goodman. 2009. Non-Uniform Corrosion in Copper Piping Monitoring Techniques. AWWARF Project 3109. Denver, CO. Edwards, Marc, Jeffrey Parks, Allian Griffin, Meredith Raetz, Amanda Martin, Paolo Scardina, and Carolyn Elfland. 2011. Lead and Copper Corrosion Control in New Construction. WaterRF Project 4164. Denver, CO. Edwards, M.. 2012. Discussion Article Galvanic Effect on Lead and Copper Release. Journal AWWA, 2012. Denver, CO. Eidinger, John and Craig A. Davis. 2012. Recent Earthquakes: Implications for U.S. Water Utilities. WaterRF Project 4408. Denver, CO. Eisenbeis, P., P. Le Gauffre, and S. Saegrov. 2000. Water Infrastructure Management: An Overview of European Models and Databases. Presentation at AWWA Infrastructure Conference. Baltimore, MD. Ellison, Dan, Andy Romer, Ray Sterling, David Hall, and Michael Grahek. 2006. No-Dig and Low-Dig Service Connections Following Water Main Rehabilitation. AWWARF Project 2872. Denver, CO. Ellison, Dan, Firat Sever, Peter Oram, Will Lovins, Andrew Romer, Steven J. Duranceau, and Graham Bell. 2010. Global Review of Spray-On Structural Lining Technologies. WaterRF Project 4095. Denver, CO. Ellison, Dan, Graham E.C. Bell, Don Ballantyne, Thomas D. O'Rourke. 2012. Selection of Water Main Materials for the Los Angeles Department of Water and Power. LADWP. Los Angeles, CA. Ellison, Dan, Romer, A., Bell, G., and O Brien, A. 2001. Distribution Infrastructure Management: Answers to Common Questions. AWWARF Project No. 2629, Denver, CO. Ellison, Dan. 2003. Investigation of Pipe Cleaning Methods. AWWARF Project 2688. Denver, CO. Folgherait, Brian, Ryan Rogers and Shawn Kirsch. 2013. Water Main Rehabilitation Using Polyurea Linings Same Day Return to Service. Presentation at the North American Society for Trenchless Technology No-Dig Conference. Sacramento, CA. Folkman, Steven. 2012. Water Main Break Rates in the USA and Canada: A Comprehensive Study. Utah State University Buried Structures Laboratory. Logan, UT. Friedman, Melinda J., Andrew S. Hill, Steve H. Reiber, Richard L. Valentine, and Gregory V. Korshin. 2010. Assessment of Inorganics Accumulation in Drinking Water System Scales and Sediments. WaterRF Project 3118. Denver, CO. Friedman, Melinda, Gregory Kirmeyer, Jason Lemieux, Mark LeChevallier, Steven Seidl, and Jan Routt. 2010. Criteria for Optimized Distribution Systems. WaterRF Project 4109. Friedman. M., A. Hill, S. Reiber, R. Valentine, and G. Korshin. 2010. Assessment of Inorganics Accumulation in Drinking Water System Scales and Sediments. Denver, Colo.: Water Research Foundation. Gaewski, Peter E. and Frank J. Blaha. 2007. Analysis of Total Cost of Large Diameter Pipe Failures. AWWARF. Denver, CO.

References 217 Giammar, Daniel E., Katherine S. Nelson, James D. Noel, and Yanjiao Xie. 2010. Influence of Water Chemistry on the Dissolution and Transformation Rates of Lead Corrosion Products. WaterRF Project 4064. Denver, CO. Graham, Andrew, Gregory J. Kirmeyer, Eric Wessels, Edward Tenny, Doug Harp; Scott McKinney, Chris Saill, Bud Templin, David Hughes, and John Fortin. 2008. Asset Management Research Needs Roadmap. AWWARF Project 4002. Grigg, Neil S. 2004. Assessment and Renewal of Water Distribution Systems. AWWARF Project 2772. Denver, CO. Grigg, Neil S. 2007. Main Break Prediction, Prevention, and Control. AWWARF Project 461. Grigg, Neil S. 2009. Secondary Impacts of Corrosion Control on Distribution System and Treatment Plant Equipment. AWWARF Project 4029. Denver, CO. Gustafson, Jan-Mark, Chris Macey, Ross Homeniuk, D. Griffin. 2007. A Case for Installing an Anode with Every Repair of a Cast Iron Water Main Almost. Presentation at AWWA Annual Conference and Exhibition. Toronto, Canada. Hannaford, M. A., W. J. Melia, P. M. Hoyt, R. Z. Jackson, 2010, An Advanced Method of Condition Assessment for Large-Diameter Mortar-Lined Steel Pipelines. Presentation at AWWA Annual Convention and Exhibition, Chicago, IL. Harrington, T.D., 1985. Nuts and Bolts of a Corrosion Control Program. AWWA Seminar Proceedings. Distribution System Symposium. Seattle, WA. Helgeson, D. R. 1985. Basic Corrosion and How it Affects Utility Operations. AWWA Seminar Proceedings. Distribution System Symposium. Seattle, WA. Hu, Yafei, Dunling Wang, and Rudaba Chowdhury. 2012. Long Term Performance of Asbestos Cement Pipe. WaterRF Project 4093. Denver, CO. Huebler, James, Maurice Givens, Chris Ziolkowski, and Kiran Kothari. 2009. Commercialization of the Digital Leak Detector. WaterRF Project 4041. Denver, CO. Hughes, David M. 2002. Assessing the Future: Water Utility Infrastructure Management. AWWA. Denver, CO. Hughes, David M., Yehuda Kleiner, Balvant Rajani, and Jean-Eric Sink. 2011. Continuous System Leak Monitoring-From Start to Repair. WaterRF Project 3183. Denver, CO. Hunaidi, Osama. 2000. Leak Detection Methods for Plastic Water Distribution Pipes. AWWARF Project 393. Denver, CO. Jackson, Rodney Z., Charles Pitt, and Ronald Skabo. 1992. Nondestructive Testing of Water Mains for Physical Integrity. AWWARF Project 507. Denver, CO. Kirmeyer, G., T. Thomure, R. Rahman, J. Marie, M.W. LeChevallier, J. Yang, D.M. Hughes, and O. Schneider. [N.d] Effective Microbial Control Strategies for Main Breaks and Depressurization. Water Research Foundation. Forthcoming. Kirmeyer, Gregory J., Jonathan Clement, and Anne Sandvig. 2000. Distribution System Water Quality Changes Following Implementation of Corrosion-Control Strategies. AWWARF Project 157. Denver, CO. Kirmeyer, Gregory J.. 2000. Lead Pipe Rehabilitation and Replacement Techniques. AWWARF Project 465. Denver, CO. Kirmeyer, Gregory. J., William Richards, Charlotte Dery Smith. 1995. An Assessment of Water Distribution Systems and Associated Research Needs. AWWARF Project 706. Denver, CO. Kleiner, Yehuda and Balvant Rajani. 1992. Using Limited Data to Assess Future Needs. Journal AWWA. 91(7):47-61.

218 Answers to Challenging Infrastructure Management Questions Kleiner, Yehuda and Balvant Rajani. 2010. Dynamic Influences on the Deterioration Rates of Individual Water Mains (I-WARP). WaterRF Project 3052. Denver, CO. Kleiner, Yehuda, Balvant Rajani, and Rehan Sadiq. 2005. Risk Management of Large-Diameter Water Transmission Mains. AWWARF Project 2883. Denver, CO. Klopfer, Danny J. and Jeff Schramuk. 2005. Field Report -- A Sacrificial Anode Retrofit Program for Existing Cast-Iron Distribution Water Mains. Journal - American Water Works Association. December 2005, Volume 97, Number 12. Lafferty, Angela K. and William C. Lauer, 2005. Benchmarking Performance Indicators for Water and Wastewater Utilities: Survey Date and Analyses Report. Denver, Colo.: AWWA. Lander, P., L. Fendelander, and J. C. Francett. 1999. Leak Detection Surveys Using a Digital Correlator. Presentation at AWWA Distribution System Symposium. Reno, NV. Le Gouellec, Yann A. and David A. Cornwell. 2006. Installation, Condition Assessment, and Reliability of Service Lines. AWWARF Project 2927. Denver, CO. Lillie, Kevin, Christopher Reed, Mark Rodgers, Simon Daniels, and David Smart. 2004. Workshop on Condition Assessment Inspection Devices for Water Transmission Mains. AWWARF Project 2871. Denver, CO. Logsdon, G.S., and J.R. Millette. 1981. Monitoring for Corrosion of Asbestos-Cement Pipe. Proceedings of the Ninth Annual AWWA Water Quality Technology Conference. AWWA. Denver, CO. Mackellar, S. and D. Pearson. 2003. Nationally Agreed Failure Data and Analysis Methodology for Water Mains Volume 1: Overview and Findings. Report Ref. No. 03/RG/05/7, UK Water Industry Research, London, UK. Makar, J., and N. Chagnon. 1999. Inspecting Systems for Leaks, Pits, and Corrosion. Journal AWWA. 91(7):36-46. Makar, Jon, Ronald Rogge, Shelley McDonald, and Solomon Tesfamariam. 2005. The Effect of Corrosion Pitting on Circumferential Failures in Grey Cast Iron Pipes. AWWARF Project 2727. Denver, CO. Marlow, David, Paul Davis, Dung Trans, David Beale, Stewart Burn and Anthony Urquhart. 2009. Remaining Asset Life: a State of the Art Review. Strategic Asset Management and Communication. WERF. Alexandria, VA. Marlow, David R. and David J. Beale. 2012. Condition Assessment of Water Main Appurtenances. WaterRF Project 4188. Denver, CO. Marshal, B. and M. Edwards. 2013. Confirming the Role of Aluminum Solids and Chlorine in Copper Pitting Corrosion. Proceedings of AWWA Annual Conference. 2003 Matichich, Mike, Ron Booth, John Rogers, Eric Rothstein, Elisa Speranza, Cody Stanger, Ed Wagner, and Paul Gruenwald. 2005. Asset Management Planning and Reporting Options for Water Utilities. AWWARF Project 2848. Denver, CO. Matthews, John, Ryan Wensink, Erez Allouche, Shaurav Alam and Jadranka Simicevic. 2011. Performance Evaluation of Innovative Water Main Rehabilitation Spray-on Lining Product in Somerville, NJ. USEPA. Cincinnati, OH. McKim, Robert A.. 2007. Performance and Cost Targets for Water Pipeline Inspection Technologies. AWWARF Project 3065. Denver, CO. Mergelas, Brian and Xiangjie Kong. 2002. Electromagnetic Inspection of Prestressed Concrete Pipe. AWWARF Project 2564. Denver, CO.

References 219 Moser, A.P. and Kenneth G. Kellogg. 1994. Evaluation of Polyvinyl Chloride (PVC) Pipe Performance. AWWARF Project 708. Denver, CO. Muster, Tim, Paul Davis, Stewart Burn, Januar Gotama, Scott Gould, Dhammika De Silva, and Nicholas Beale. 2011. Life Expectancy of Cement Mortar Linings in Cast and Ductile Iron Pipes. WaterRF Project 3126. Denver, CO. Nestleroth, Bruce, Stephanie Flamberg, Wendy Condit, John Matthews, Lili Wang and Abraham Chen. 2012. Field Demonstration of Innovative Condition Assessment Technologies for Water Mains: Leak Detection and Location. USEPA. Cincinnati, Ohio. NICTA, 2012. "A New Technique for Water Pipe Condition Prediction". Report for Sydney Water by National Information and Communicatonis Technology of Australia. O'Day, D. Kelly, R. Weiss, S. Chiavari, D. Blair. 1986. Water Main Evaluation for Rehabilitation / Replacement. AWWARF Project 54. Denver, CO. Ong, Say Kee, James A. Gaunt, Feng Mao, Chu-Lin Cheng, Lidia Esteve-Agelet, and Charles R. Hurburgh. 2008. Impact of Hydrocarbons on PE/PVC Pipes and Pipe Gaskets. AWWARF Project 2946. Denver, CO. Oxenford, Jeffrey L., David M. Hughes, Eugenio Giraldo, Jerry K. Snyder, Arun K. Deb, Stewart Burn, David Main, Jane Olivier, James S. Wailes, and Brian Naess. 2012. Key Asset Data for Drinking Water and Wastewater Utilities. WaterRF Project 4187. Denver, CO. Parks, Jeffrey, Marc Edwards, Peter Vikesland, Matthew Fiss, and Abhijeet Dudi. 2008. Autogenous Healing of Concrete in the Drinking Water Industry. AWWARF Project 3090. Denver, CO. Pierson, Greg, Katherine Martel, Andrew Hill, Gary Burlingame, Alan Godfree. 2001. Practices to Prevent Microbial Contamination of Water Mains. AWWARF Project 2610. Denver, CO. Pollard, Simon, Steve Hrudey, Paul Hamilton, Brian MacGillivray, John Strutt, John Sharp, Roland Bradshaw, William Leiss, and Alan Godfree. 2007. Risk Analysis Strategies for Credible and Defensible Utility Decisions. AWWARF Project 2939. Denver, CO. Rajani, Balvant, Yehuda Kleiner, and Dennis Krys. 2011. Long-Term Performance of Ductile Iron Pipes. WaterRF Project 3036. Denver, CO. Rajani, Balvant. 2000. Investigation of Grey Cast Iron Water Mains to Develop a Methodology for Estimating Service Life. AWWARF Project 280. Denver, CO. Reed, Chris, David Smart, and Alastair Robinson. 2006. Potential Techniques for the Assessment of Joints in Water Distribution Pipelines. AWWARF Project 2689. Denver, CO. Reed, Chris, David Smart, and Alastair Robinson. 2004. Techniques for Monitoring Structural Behavior or Pipeline Systems. AWWARF Project 2612. Denver, CO. Reiber, S.. 2009. Drinking Water Utilities, Forensics and Litigation, Proceedings of the WQTC. Reiber, Steven H. and Glenn Dostal. 2000. Arsenic and Old Pipes A Mysterious Liaison, Well Water Disinfection Sparks Surprises, Opflow, Vol. 26 No. 3, March 2000. Reiber, Steven. 1993. Chloramine Effects on Distribution System Materials. AWWARF Project 508. Denver, CO.

220 Answers to Challenging Infrastructure Management Questions Renaud, E., Y. Le Gat and M. Poulton. Using a Break Prediction Model for Drinking Water Networks Asset Management: From Research to Practice. International Water Association, 4th Leading Edge Conference on Strategic Asset Managemen, September 27-30, 2011, Mülheim An Der Ruhr, Germany. Richardson, Ruth and Marc Edwards. 2009. Vinyl Chloride and Organotin Stabilizers in Water Contacting PVC Pipes. AWWARF Project 2991. Denver, CO. Rockaway, Thomas D. and R. Timothy Ball. 2007. Guidelines to Minimize Downtime During Pipe Lining Operations. AWWARF Project 2956. Denver, CO. Rockaway, Thomas D., Gerold A. Willing, Raymond M. Schreck, and Kenneth R. Davis. 2007. Performance of Elastomeric Components in Contact with Potable Water. AWWARF Project 2932. Denver, CO. Romer, Andrew E. and Graham E. C. Bell. 2005. External Corrosion and Corrosion Control of Buried Water Mains. AWWARF Project 2608. Denver, CO. Romer, Andrew E., Graham E. C. Bell, Dan Ellison, and Brien Clark. 2008. Failure of Prestressed Concrete Cylinder Pipe (PCCP). AWWARF Project 4034. Denver, CO. Romer, Andrew E., Graham E. C. Bell, Dan Ellison, and Brien Clark. 2008. Failure of Prestressed Concrete Cylinder Pipe (PCCP). AWWARF Project 4034. Denver, CO. Rose, Duncan, Rob Green, Joe North, and Linda Blankenship. 2009. Benefit Cost Analysis Tool. WaterRF Project 4127. Denver, CO. Rozental, Magali. 2009. The Life-Cycle of Polyethylene. Presentation to ASTEE, Nice, France, June 12, 2009 by Suez Environnement. Ryder, R.A. 1980. The Cost of Internal Corrosion in Water Systems. Journal AWWA. 280(5):267-279. Sadiq, Rehan, Syed A. Imran, and Yehuda Kleiner. 2007. Examining the Impact of Water Quality on the Integrity of Distribution Infrastructure. AWWARF Project 3127. Denver, CO. Sadiq, Rehan, Yehuda Kleiner, and Yehuda Kleiner. 2009. Proof-of-Concept Model to Predict Water Quality Changes in Distribution Pipe Networks. AWWARF Project 2970. Denver, CO. Sandvig, A. M., P. Kwan, G. Kirmeyer,, B. Maynard, D. Mast, S. Trussel, A. Cantor, and A. Prescott. 2008. Contribution of Service Lines and Plumbing Fixtures to Lead and Copper Rule Compliance Issues. Water Research Foundation. Denver, CO. Sandvig, Anne, Pierre Kwan, Gregory Kirmeyer, Barry Maynard, David Mast, R. Rhodes Trussell, Shane Trussell, Abigail Cantor, and Annette Prescott. 2008. Contribution of Service Line and Plumbing Fixtures to Lead and Copper Rule Compliance Issues. AWWARF Project 3018. Denver, CO. Sarver, Emily, Yaofu Zhang, and Marc Edwards. 2011. Copper Pitting and Brass Dezincification: Chemical and Physical Effects. WaterRF Project 4289. Denver, CO. Scardina, P. and M. Edwards. 2008. Assessment of Non-Uniform Corrosion on Copper Piping. AWWA Research Foundation. Denver, CO. Schneider, Orren D., Jeffrey Parks, Marc Edwards, Amrou Atassi, and Anusha Kashyap. 2011. Comparison of Zinc vs. Non-Zinc Corrosion Control for Lead and Copper. WaterRF Project 4103. Denver, CO. Smulders, F.P.A., ed. 1999. Maintenance and Rehabilitation Strategy for Water Supply Systems in the Netherlands. Presentation at AWWA Distribution System Symposium. Reno, NV.

References 221 Stone, Steve, Emil J. Dzuray, Deborah Meisegeier, AnnaSara Dahiborg, and Manuela Erickson. 2002. Decision-Support Tools for Predicting the Performance of Water Distribution and Wastewater Collection. US EPA/600/R-02/029 Stratus Consulting, Inc. 1998. Infrastructure Needs for the Public Water Supply Sector. Report prepared for AWWA Government Affairs. Boulder, CO. Thacher, Jennifer, Megan Marsee, Heidi Pitts, Jason Hansen, Janie Chermak, and Bruce Thomson. 2011. Assessing Customer Preferences and Willingness to Pay: A Handbook for Water Utilities. WaterRF Project 4085. Denver, CO. The Copper Development Association. 2012. http://www.copper.org/environment/nace02122/ nace02122c.html) Thompson, Craig and David Jenkins. 1987. Review of Water Industry Plastic Pipe Practices. AWWARF Project 104. Denver, CO. Thompson, D.M. and S.A. Weddle. 1992. Water Utility Experience With Plastic Service Pipe. AWWARF Project 414. Denver, CO. Thomson, James and Lili Wang. 2009. State of Technology Review Report on Condition Assessment of Ferrous Water Transmission and Distribution Systems. USEPA. Triantafyllidou, S. 2008. Addressing and Assessing Lead Threats in Drinking Water, Non- Leaded Brass, Product Testing, Particulate Lead Occurrence and Effect of Chloride to Sulfate Mass Ratio Effects on Corrosion. Masters Thesis, Virginia Polytechnique Institute. Blacksburg, VA. Urquhart, Anthony and Stewart Burn. 2008. Condition Assessment Strategies and Protocols for Water and Wastewater Assets. AWWARF Project 3048. Denver, CO. USEPA. 2009. Drinking Water Infrastructure Needs Survey and Assessment - Fourth Report to Congress. EPA/816/R-09/080, U.S. EPA Office of Water, Washington, D.C. Van den Berg, Caroline. 1997. Water Privatization and Regulation in England and Wales, Public Policy for the Private Sector. World Bank Group Note No. 15. Von Huber, H. 1999. Selecting a Valve and Pipe Locator. Opflow, 25(9)12-14. Walker, K., M. Graves and S. Reiber. 2012. An Innovative Approach to Aeration for THM Control. Proceedings of the WQTC. Toronto, Canada. Washington Suburban Sanitary Commission. 2008. Copper Pinhole Leak Investigation Summary.http://www.wsscwater.com/file/EngAndConst/InfrastructSystems/Investigation %20Fact%20Sheet.pdf Zarghamee, Mehdi S., Rasko P. Ojdrovic, and Peter D. Nardini. 2012. Pre-stressed Concrete Cylinder Pipe Condition Assessment - What Works, What Doesn't, What's Next. WaterRF Project 4233. Denver, CO. Zhang, Y. 2009. Nitrification in Premise Plumbing and its Impact on Corrosion. Masters Theses, Virginia Polytechnique Institute. Blacksburg, VA. Zhang, Y.. 2009. Dezincification and Brass Lead Leaching in Premise Plumbing Systems: Effects of Alloy, Physical Condition and Water Chemistry, Masters Thesis Virginia Polytechnique Institute. Blacksburg, VA Zhang, Yan, Marc Edwards, Ameet Pinto, Nancy Love, Anne Camper, Mohammad Rahman, and Helene Baribeau. 2010. Effect of Nitrification on Corrosion in the Distribution System. WaterRF Project 4015. Denver, CO. Ziolkowski, Christopher. 2008. Development of an Advanced Tracer Wire Terminator/Coupler. AWWARF Project 3050. Denver, CO.

ABBREVIATIONS AC AMR ASR ASTM AWWA CCTV CI CIPP CIS CML CMMS CP Asbestos cement Automatic meter reading Alkali-silica reaction/reactivity ASTM International, formerly American Society for Testing and Materials American Water Works Association Closed-circuit television Cast iron Cured-in-place pipe Customer information system Cement mortar lining Computerized Maintenance Management System Cathodic protection DBP DI DMA Disinfectant byproducts Ductile iron District meter area EBMUD ECN Ecorr EDS EMT EPA East Bay Municipal Utility District Electrochemical noise Corrosion potential Energy dispersive spectroscopy Electromagnetic test Environmental Protection Agency F&A Finance and accounting GIS GPR GPS Geographical information system Ground penetrating radar Global positioning system HDD HDPE HPC Horizontal directional drilling High-density polyethylene Heterotrophic plate count ID IT Inside diameter Information technology 223

224 Answers to Challenging Infrastructure Management Questions LADWP LCR LEED LI LPR Los Angeles Department of Water and Power Lead and Copper Rule Leadership in Energy and Environmental Design Langlier Index Linear polarization resistance MDPE MFL mg/l NASSCO NACE NDE NSF Medium-density polyethylene Magnetic flux leakage Milligrams per liter National Association of Sewer Service Companies NACE International (formerly National Association of Corrosion Engineers) Non-destructive examination National Sanitary Foundation OD OFWAT Outside diameter Water Services Regulation Authority of England and Wales PACP PCCP PE PSI PVC PVCO Pipeline Assessment Certification Program of NASSCO Prestressed concrete cylinder pipe Polyethylene Pounds per square inch Polyvinyl chloride Oriented PVC RCP RFEMT RFTC RO Reinforced concrete pipe Remote-field electromagnetic test or technique Remote-field, transformer coupled Reverse osmosis SAM-GAP SCCP SEM SEM/EDS SIMPLE SSPC Strategic asset management gap Steel cylinder concrete pipe Scanning electron microscope SEM/Energy dispersive spectroscopy Sustainable Infrastructure Management Program Learning Environment Society for Protective Coatings (formerly Steel Structures Painting Council) UK U.S. UT United Kingdom United States of America Ultrasonic test

Abbreviations 225 WERF WRc Water Environment Research Foundation Water Research Council ZOP Zinc orthophosphate